BIOLOGY REVIEWER 1Q Characteristics of Life: 1. All organisms are made up of cells. The structure of cells differ in organisms such as in plant and animal cels. 2. Organisms are capable of reproduction to sustain their species. 3. The character traits in the DNA of organisms help them grow and develop, 4. Organisms utilize energy to be used in specific functions. 5. Organisms can adjust to changes in the environment (adaptation). 6. Maintaining the balance or steady state of their system (homeostasis). 7. Organisms are capable of evolving themselves to interact better in their environment. * ATP (Adenosine Triphosphate) - energy source of cells Famous Biologists • Robert Hooke - first to use the term cells and responsible for the beginning of cytology • Anton Van Leeuwenhoek - discovered the first microscope; discovered microscopic organisms in rainwater and observed plant and animal cells • Jean Baptiste Pierre Antoine de Monet - proposed that cells are filled with fluids • Robert Brown - discovered nuclei cells • Matthias Schleiden & Theodore Schwann - introduced the concept that all plants and animals are made of cells • Rudolf Virchow - found that cells divide to form new cells and concluded that cells come from pre-existing cells • Louis Pasteur - studied microorganisms such as bacteria and proposed pasteurization (or the process of removing microorganisms using heat and pressure) THE CELL - building blocks of life - basic membrane-bound unit that contains the fundamental molecules (protein, carbohydrates, lipids) of life and of which all living things are composed - basic structural, functional, and biological unit of life Cell Theory: 1. All living things are composed of cells. (Matthias Schleiden, Theodore Schwann) 2. Cells are the basic units of life and function in living things. 3. All cells are produced from other cells. (Rudolf Virchow) 2 Primary Types of Cells: 1. Prokaryotic Cell - unicellular; bacteria 2. Eukaryotic Cell - multicellular; protists, fungi, animals, plants PROKARYOTIC EUKARYOTIC no membrane-bound organelles membrane-bound organelles (such as nucleus) usually unicellular (cyanobacteria can be multi) usually multicellular PROKARYOTIC EUKARYOTIC in bacteria & archaea in plants & animals no lysosomes/peroxisomes has lysosomes/peroxisomes no ER has ER no mitochondria has mitochondria no Golgi apparatus has Golgi apparatus smaller ribosomes larger ribosomes 3 Major Parts of the Cell: 1. plasma membrane/cell wall (external coverings and locomotive organs) 2. nucleus 3. cytoplasm PLANT CELL ANIMAL CELL have plastids (e.g. chloroplast) do not have plastids have a cell wall (made of cellulose) no cell wall (instead: plasma membrane) have a large central vacuole have small, temporary vacuoles (if any) may have plasmodesmata do not have plasmodesmata do not have centrioles have paired centrioles within centrosome do not have cholesterol in cell membrane have cholesterol in the cell membrane store excess glucose as starch store excess glucose as glycogen generally have a fixed, regular shape generally have an amorphous shape * plasmodesmata - channels/bridges; coordinate with other cells Plastids (Chloroplasts) - found only in plants and serves as sites of photosynthesis storage of starch ‣ chloroplastids - contain chlorophyll (green) ‣ xanthophylls - yellow pigments ‣ carotenes - orange pigments ‣ leucoplastids - colorless pigments CELL STRUCTURES AND FUNCTIONS Cell Structures for PROTECTION 1. Plasma Membrane - animal cell - composed of phospholipid bilayer - selectively permeable - separates cells from other cells m. ocampo - also called cell membrane - a thin barrier that forms a boundary separating an individual cell from external environment - a living system that controls passage of needed materials into and out of the cell - passage of important molecules, ions, and gases between outside and inside of the cell 2. Cell Wall - plant cell and prokaryotes - provides framework - thick layer composed of cellulose - protects and gives support to the cell - made up of polysaccharide cellulose - the cell wall of plants/algae have channels to let the water diffuse (move outward) - fungi: cell walls are made up by chitin - bacteria: cell walls are up by peptidoglycan 3. Phospholipid Bilayer - composed of two layers of phospholipid - head: hydrophilic (loves water) - tail: hydrophobic (afraid of water) - embedded with proteins and carbohydrates sandwiched between the layers - acts as a semipermeable membrane (only permits certain kinds of molecules, mainly simple molecules like water and glucose) - doesn’t permit large and complex molecules (such as starch)—can enter the cell via the protein channels with the use of energy CYTOPLASM AND THE ORGANELLES 1. Cytoplasm - the semi-solid, semiliquid, gel-like substance that holds the internal structures of the cell - serves as a medium of transport - holds all the organelles (“little organs”) of the cell - fills the space between the nucleus and the cell membrane - cytosol: the fluid portion consisting of water and excluding organelles in it 2. Organelles - are little organs that perform specific functions inside the cell - endomembrane system: refers to the group of organelles that produce and transport substances on the cytoplasm through the use of vesicles GENETIC CONTROL ORGANELLES 1. Nucleus - “Brain of the Cell” - contains a denser, darker sphere in the center called nucleolus (contains the RNA that contains the code to make proteins in the ribosomes) - storehouse of genetic information; chief operating officer: directs all acts - performs crucial tasks such as protecting DNA - nuclear envelope: encloses DNA that is filled up with holes - nuclear pores: allows large molecules to pass between the nucleus and the cytoplasm 2. Ribosomes - “Protein Factories of the Cell” - very small, dot-like structure - function mainly to make proteins (receives instructions via RNA/mRNA produced in the nucleus M A N U FA C T U R I N G , S T O R A G E , D I S T R I B U T I O N , A N D BREAKDOWN ORGANELLES 1. Endoplasmic Reticulum - “Manufacturers of the Cell” - manufactures various organic compounds - serves as a transport membrane across the cell - 2 types: smooth ER & rough ER Smooth Endoplasmic Reticulum - tube-like structure next to the rough ER - has no ribosomes - functions in synthesis of lipids, phospholipids, and steroids (all fats) Rough Endoplasmic Reticulum - rough because of ribosomes attached - together with ribosomes, they produce secretory proteins that are to be transported out of the cell 2. Golgi Body - “Packaging of the Cell” - functions in transport of molecules made by the ER via transport vesicles - appears like a stack of pancakes - they modify, sort, pack, and finally ship the molecules outside and inside the cell - transport vesicles: circular containers from the Golgi body that is used for shipping; freely moves in and out of the cell 3. Vacuole and Vesicles - “Water Tank of the Cell” - vacuole: functions primarily in the storage of water and dissolved substances - vesicles: smaller versions of vacuoles, mainly for transport - vacuoles are larger in plant cells than in animal cells - in plant cells, there is usually a single, central vacuole - in animal cells, there are many vacuoles scattered in the cytoplasm 4. Lysosomes - “Waste Disposal of the Cell” - produces hydrolytic enzymes called lysozyme (digests and destroys molecules and organelles that are not needed anymore by the cell) - protects the cell by destroying foreign substances - molecules to be destroyed are carried by the vesicles - can destroy the whole cell itself 5. Peroxisomes - “Waste Disposal of the Cell” - have oxidative enzymes which breaks down long chains of fatty acids and lipids—fats) - has a lipid bilayer membrane ENERGY PRODUCING ORGANELLES 1. Mitochondria - “Powerhouse of the Cell” - sausage-shaped, composed of phospholipid bilayer m. ocampo - its inner structure is called the matrix (because it’s like a maze) - produces energy in the form of ATP molecules 2. Chloroplasts - “Food Manufacturer of the Cell” - capsule-shaped - contains chlorophyll molecules which is the location of photosynthesis - present only in plant cell and animal autotrophs like planktons ORGANELLES FOR STRUCTURAL SUPPORT, MOVEMENT, AND COMMUNICATION SKILLS 1. Centrioles - rod-like - aids in cell division - during cell division, they produce fibers to pull the chromosome to opposite poles of the cell (mitosis) - composed of microtubule units 2. Flagella & Cilia - appendages attached to the plasma membrane; for movement - cilia: has absorption properties that help the roots get water and lungs to filter the incoming air 3. Cytoskeleton - “Framework of the Cell” - provide structural support like bones - composed of actin filaments and microtubules 4. Ribosomes - 2 types: ‣ free ribosomes - floating free in the cytoplasm ‣ attached ribosomes - mostly in the rough ER Centrioles in Cell Division - centrioles produce spindle fibers that pull away the chromosomes at the end of each pole - it is necessary to pull the chromosomes at both poles because they contain DNA TISSUE - a group of cells similar in structure and in function Four Types of Tissues: 1. Epithelial Tissue 2. Connective Tissue 3. Muscle Tissue 4. Nervous Tissue Epithelial Tissue Functions: ‣ protection: covers surfaces of the body ‣ absorption: lies in small intestines ‣ secretion: forms glands ‣ filtration: blood vessels Types of Epithelial Tissues based on Layers: a. simple - one layer b. stratified - two or more layers c. pseudostratified - one layer but appears to be more than one Types of Epithelial Tissues based on Shape: a. squamous - flat cells b. cuboidal - cube-shaped c. columnar - rectangular or column shaped d. transitional - have the ability to change in shape Connective Tissue Functions: ‣ protection for internal organs: skull protects the brain ‣ structural support: bones provide framework ‣ connection: ligament connects bone to bone, tendon connects muscle to bone ‣ storage: bones store calcium and phosphorous ‣ transportation: blood transports nutrients, gases, and wastes throughout the body ‣ immune: WBCs protect the body from foreign invaders Examples: • dense connective tissue • adipose tissue, areolar tissue • compact bone • blood Muscle Tissue - a specialized tissue found in animals which functions by contracting, thereby applying forces to different parts of the body Types of Muscle Tissue: a. Skeletal Muscle - attach to and move bones by contracting and relaxing in response to voluntary messages from the nervous system - composed of long cells called muscle fibers that have a striated appearance - voluntary; striated b. Smooth Muscle - found in the walls of hollow organs throughout the body - involuntary movements triggered by impulses that travel through the autonomic nervous system to the smooth muscle tissue - component of the digestive, urinary, and reproductive systems - involuntary; non-striated c. Cardiac Muscle - forms the contractile walls of the heart - only found in the heart, where it performs coordinated contractions that pump blood throughout the circulatory system - involuntary; striated Nervous System - function: consists of neurons and supporting cells called neuroglia ‣ neurons - highly specialized nerve cells that generate and conduct nerve impulses ‣ dendrites - responsible for responding to stimuli; they receive incoming signals towards the cell body ‣ axons - responsible for transmitting impulses over long distances away from cell body ‣ cell body - is like a factory for the neuron; it produces all the proteins and contains specialized organelles such as nucleus, granules and Nissl bodies m. ocampo Blood Cells 1. Red Blood Cells - aka erythrocytes - cells that circulate in the blood and carry oxygen throughout the body 2. White Blood Cells - aka leukocytes - a cellular component of the blood that defend the body against infection and disease by ingesting foreign materials and cellular debris, by destroying infectious agents and cancer cells, or by producing antibodies a. neutrophils - mainly target bacteria and fungus; increase during bacterial infection b. basophils - mainly responsible for allergic reactions c. eosinophils - target larger parasites, such as worms, and modulate allergic inflammatory responses d. monocytes - serve as part of the defense particles; when a monocyte is found in tissue, it is called a macrophage e. lymphocytes - work the front lines to identify and destroy foreign invaders; they make antibodies (protective protein produced by the immune system in response to the presence of a foreign substance) and help kill tumor cells 3. Platelets - aka thrombocytes - tiny blood cells that help the body form clots to stop bleeding MICROSCOPE - “micro” - small - “skopion” - to see or look - instrument that produces enlarged images of small objects, allowing the observer an exceedingly close view of minute structures at a scale convenient for examination and analysis History of the Microscope DATE SCIENTIST CONTRIBUTION 1st century AD (year 100) Early Romans invention of glass magnifiers or burning glasses 14th century Italians spectacle makers were producing lenses to be worn as glasses 1590 Hans & Zacharias Janssen created the very first simple microscope (simply a tube with lenses at each end) 1675 Anton van Leeuwenhoek developed a specialized microscope for the observation of microorganisms, plan and animal cells; the first to observe becteria 1932 Frits Xernike invention of the phase-contrast microscope 1938 Ernst Ruska discovered electron microscope Microscope Parts and Functions 1. Eyepieces - the lenses at the top that the viewer looks through 2. Body tube - connects the eye pieces to the objective lenses 3. Base - the bottom of the microscope—what the microscope stands on 4. Arm - structural element that connects the head of the microscope to the base 5. Stage - the flat platform that supports the slides; stage clips hold the slides in place 6. Objective lenses - used to magnify the images of the specimen to form an enlarged image ‣ scanner (red) - magnifies 4x ‣ low power objective (yellow) - 10x ‣ high power objective (blue) - 40x ‣ oil immersion objective (white) - 100x 7. Nose piece - holds the objective lenses and be turned to increase the magnification 8. Coarse adjustment knob - located on the arm of the microscope and moves the stage up and down to bring the specimen into focus 9. Fine adjustment knob - used to bring the specimen into sharp focus under high power lenses 10. Diaphragm - used to collect and focus the light from the illuminator on to the specimen 11. Condenser - controls the size of the light beam; it gathers light from the mirror and directs it to the objective lens 12. Light source - source of light to illuminate the specimen REPRODUCTION OF CELLS Cell Division - cells divided and new cells are produced for growth and to replace damaged, old cells or worn out tissues, development and reproduction - differs in prokaryotes (bacteria) and eukaryotes (protists, fungi, plants & animals) Cell are Identical ‣ instructions for making cell parts are encoded in the DNA (the cell’s new genetic material ‣ each new cell must get a complete set of DNA molecules m. ocampo ‣ DNA must undergo replication before cell division, each new cell will then have an identical copy of the DNA - the cell increases in mass and/or size and becomes mature Chromosomes - thread-like structures in which DNA is tightly packaged within the nucleus - physical carriers of genes, consisting of DNA and associated proteins - have the capacity to transmit genes during cell division - the longest phase of interphase - organelles divide and increase in number in preparation for - DNA is tightly coiled around proteins called histones, which provide the structural support - human body cells have 46 chromosomes or 23 identical pairs - duplicated chromosomes are called chromatids and are held together by the centromere Karyotype - is simply a picture of a person’s cell chromosomes arranged in pairs and size - to get the picture, chromosomes are isolated, stained, and examined under the microscope - autosomes: first 22 pairs - sex chromosomes: last pair / XX female or XY male Types of Cell Reproduction 1. Asexual reproduction - single cell dividing to make 2 new, identical daughter cells (ex: mitosis/eukaryotes, binary fission/ bacteria) 2. Sexual reproduction - two cells (egg & sperm) joining to make a new cell (zygote) that is NOT identical to the original cells (ex: meiosis) THE CELL CYCLE - the period of growth, maturation, and reproduction of the cell described as the cell cycle Three Major Stages: 1. interphase 2. mitotic phase 3. cytokinesis 1. INTERPHASE - the longest phase in cell cycle - the cell prepares for cell division - the performs its regular functions, taking in nutrients and growing A. Gap 1 (G1) Stage - first primary growth phase by making more cytoplasm and organelles cell division - cell carries on its normal metabolic activities B. Synthesis (S) Stage - crucial part of interphase—the time when DNA is synthesized - begins with the replication of cellular DNA - when DNA has been replicated, the cell has twice as many chromosomes as before; it is then ready to move to the G2 Stage C. Gap 2 (G2) Stage - comes after DNA replication/synthesis - second growth stage of the cell - occurs after DNA has been copied - cell synthesizes proteins (histones) and enzymes (kinases) needed for mitosis - continues to increase in size - all cell structures needed for division are made (ex. centrioles) - both organelles & proteins are synthesized 2. MITOSIS - is initiated after the completion of interphase - occurs in a short period - the division of nucleus happens (Karyokinesis) - has four phases: A. Prophase - chromatin in nucleus condenses to form visible chromosomes - the nuclear envelope and nucleolus starts to disintegrate and spindles form at the opposite poles of the cell - centrioles then move to opposite ends to form the mitotic spindle (composed proteins) in the cytoplasm - asters appear (mitotic spindle which surrounds each pair of centrioles) - spindle fibers called kinetochores attach to the centromere of each chromosome B. Metaphase - chromosomes, attached to the kinetochore fibers, move to the center of the cell - chromosomes are now lined up at the equator C. Anaphase - a stage characterized by the separation of the chromosomes - sister chromatids are pulled apart to the opposite poles of the cell by kinetochore fibers - the two cell poles also move farther apart D. Telophase - sister chromatids at opposite poles - spindle disassembles - nuclear envelope forms around each set of sister chromatids - nucleolus reappears - chromosomes reappear as chromatin - development of cleavage furrow m. ocampo 3. CYTOKINESIS - follows right after the process of mitosis and completes the full stage of the cell cycle - division of cell into two, identical halves called daughter cells - occurs when the cytoplasm from the original cell divides and forms new cells - separates the organelles and other cytoplasmic inclusions - in most cases, the two new cells formed are equal in size Daughter Cells - have the same number of chromosomes as each other and as the parent cell from which they were formed - identical to each other, but smaller than parent cell - must grow in size to become mature cells (G1 of Interphase) Cell Cycle Checkpoints - monitor or check the progression and integrity of cell before it undergoes the next phase - stages at which the cell examines internal and external cues and "decides" whether or not to move forward with division 1. G1/S or G1 Checkpoint - checks for the size and integrity of the cell and its DNA - cells that do not reach their adequate size or those that have DNA damage are arrested, unless they are corrected - normal cells are allowed to proceed to the next stage 2. G0 Checkpoint - resting point of all cells – normal cells are “called back” and return to the cycle - non dividing cells (neurons) and arrested cells proceed 3. G2/M or G2 Checkpoint - prior to mitosis - checks the integrity of the DNA and if the cell completely and successfully undergone the interphase (G1, S and G2) - if the cell is faulty, it is arrested again 4. M Checkpoint or Spindle Checkpoint - occurs during mitosis during the end of metaphase - checks the proper alignment of chromosomes and if spindle fibers are attached to the kinetochores MEIOSIS - a process where a single cell divides twice to produce four cells containing half the original amount of genetic information - involves a "parent" cell splitting into two or more "daughter" cells—the parent cell can pass on its genetic material from generation to generation - daughter cells contain half the number of chromosomes as the original cell - produces gametes (eggs & sperm) - occurs in the testes in males (spermatogenesis) - occurs in the ovaries in females (oogenesis) Haploid vs. Diploid - diploid cells: contain two complete sets (2n) of chromosomes - haploid cells: have half the number of chromosomes (n) as diploid; contains only one complete set of chromosomes Meiosis - occurs over the course of two rounds of nuclear divisions (meiosis I and meiosis II) - Meiosis I: homologous pairs separate during a first round of cell division - Meiosis II: sister chromatids separate during the second round Meiosis Meiosis II I. MEIOSIS I A. Prophase I - homologous chromosomes undergo pairing/synapsis - crossing over takes place = tetrad - nuclear membrane disappears - spindle is formed between the centrioles B. Metaphase I - the paired chromosomes aligned on the equatorial plate with their centromeres attached to the spindle fibers - one centromere per spindle fiber C. Anaphase I - homologous chromosomes of each pair separate and move to their respective poles - the sister chromatids of each chromosome, however, remain attached to one another and don't come apart D. Telophase I - the chromosomes arrive at opposite poles of the cell; each pole has a haploid number of chromosomes - nucleus reorganizes - spindle fibers disappear - cytoplasmic division occurs forming two haploid daughter cells II. INTERKINESIS - a period of rest that cells of some species enter during meiosis, between meiosis I and meiosis II - no DNA replicated III. MEIOSIS II A. Prophase II - centrioles divide - chromatin condenses - nuclear membrane disappears - spindle fibers form B. Metaphase II - in each of the two daughter cells the chromosomes (pair of sister chromatids) line up end-to-end along the equator of the cell - the centrioles are now at opposites poles in each of the daughter cells - meiotic spindle fibers at each pole of the cell attach to each of the sister chromatids C. Anaphase II - the separated chromatids are now individual chromosomes m. ocampo - the sister chromatids are then pulled to opposite poles due ‣ primary active transport - directly uses a source of to the action of the meiotic spindle D. Telophase II - chromosomes gather at the poles - nucleoli reappear - nuclear membrane develops - spindle disappears - cytokinesis occurs forming four daughter cells (each with a haploid number of chromosomes chemical energy (e.g., ATP) to move molecules across a membrane against their gradient ‣ secondary active transport (cotransport) - uses an electrochemical gradient – generated by active transport – as an energy source to move molecules against their gradient, and thus does not directly require a chemical source of energy such as ATP - if the energy of ATP is directly used to pump molecules against their concentration gradient, the transport is called primary active transport - in some cases, the use of ATP may be indirect. For example, if a cell uses ATP to pump out Na+ and then uses the Na+ concentration gradient to bring in glucose, the transport of glucose would be an example of secondary active transport CELL TRANSPORT MECHANISMS Plasma Membrane - the cell membrane is selectively permeable or differentially permeable to carefully maintain the cell’s internal environment - it means that the membrane allows some materials to enter the cell and not all - made up of two layers of lipid (phospholipid bilayer) and layers of protein Transport Mechanisms in Cell • intracellular transport or transport of molecules within the cell is accomplished by ER and cytoplasm • transport between cells is accomplished through cell membrane Cell Transport - a process that helps cell maintain homeostasis - involves movement of molecules across the cell membrane ‣ passive transport ‣ active transport ‣ bulk/vesicular transport 3. Bulk/Vesicular Transport A. Endocytosis - a small piece of the cell membrane wraps around the particle and is brought into the cell. If the particle is solid, endocytosis is also called phagocytosis - phagocytosis: cell eating - if fluid droplets are taken in, the processes is called pinocytosis - pinocytosis: cell drinking B. Exocytosis - used by cells to secrete molecules too large to pass through the cell membrane by any other mechanism 1. Passive Transport - kind of movement of materials from a region of higher concentration to a lower concentration that does not require any metabolic energy from the cell - it relies solely on the physical properties of the substances - simple diffusion, osmosis and facilitated diffusion Simple Diffusion - is the result of the random movement of molecules - small non-charged molecules or lipid soluble molecules pass between the phospholipids to enter or leave the cell, moving from areas of high concentration to areas of low concentration Osmosis - a type of simple diffusion in which water molecules diffuse through a selectively permeable membrane from areas of high water concentration to areas of low water concentration ‣ hypotonic solution - water enters the cell, cell swells and may burst; there is increased concentration (cell lysis - bursting of cell) ‣ isotonic - no net movement of water, cell has normal size ‣ hypertonic solution - water leaves the cell, cell shrinks (crenation - shrinking of cell) Facilitated Diffusion - substances move into or out of cells down their concentration gradient through protein channels in the cell membrane 2. Active Transport - require the use of the cell’s energy, usually in the form of ATP m. ocampo
