Chapter-1
Structures and Functions of Life
Cell
All living things are made up of cells. They may be made up of
one cell (unicellular) or may be made up of many cells
(multicellular).
Cell theory (mid-nineteenth century)
(1)All living organisms are composed of cells.
(2)The cell is the basic unit of structure and organization in
organisms.
(3)Cells arise from pre-existing ones
Cells are of many different sizes and shapes. They are complex
and their components perform various functions. Our body is
made up of differently sized and shaped cells. From one
organism to another, the number of cells differs. Humans have
more cells than bacteria.
● Cells provide structure and support to the body of an
organism.
● There are many organelles bounded by a separated
membrane.
● Stem cells can transform into any type of cell.
New cells can be produced from other cells.
Two main types of cells
1.Prokaryotes
2.Eukaryotes
⁕Viruses are neither prokaryotic or eukaryotic.
1.Prokaryotes-small and simple
Prokaryotes are single-cells that lack membrane bound
organelles(Mitochondria, Golgi apparatus, chloroplast, and
lysosomes.)Prokaryotes include archaea, bacteria, and
cyanobacteria.
● Have no nucleus and no membrane bound organelles.
● The size ranges from 0.1-0.5 μm in diameter.
● DNA(circular) is in the cytoplasm
● Reproduce by binary fusion(asexual reproduction) and
conjugation
2.Eukaryotes-large and complex
Eukaryotes may be unicellular or multicellular organisms
that have nuclear membranes. They include plants, fungi,
protozoans, and animals.
● Have a true nucleus and membrane bound organelles.
● The size ranges from 10-100 μm in diameter.
● DNA(linear) is in the nucleus.
● Reproduce both sexually and asexually
Protein= a chain of amino acids
Protein= enzymes
A group of specialized cells is a specialized tissue.
A group of tissues is an organ.
A group of organs is an organ system.
Four Types of Tissues
1.Muscle tissue
2.Nervous tissue
3.Connective tissue
4.Epithelial tissue
Levels of Organization
Organelles→Cells→Tissue→Organs→Organ system
Cell Functions and components
All different cells have different specialized functions. All
cells must carry out metabolism.
Metabolism
Metabolism is a set of chemical reactions that converts
food you eat into the vital energy for maintaining life.
Cell components of a plant cell
In a plant cell, the presence of a cell wall outside the cell
membrane is one of the differences from an animal cell.
1.Cell wall(only in plant cells)- is a rigid layer outside the cell
membrane. This protects the cell and provides structural support.
It also filters molecules from passing in and out.
2.Cell membrane (plasma membrane)- is a semi-permeable
membrane that is composed of lipids and fats. This plays an
important role in regulating specific substances in and out within
the cell. It keeps toxins from entering the cell, but allows
minerals and nutrients. (in both plant and animal cells)
3.Nucleus- is a membrane-bound structure that is present only
in eukaryotic cells. It stores DNA or hereditary information
required for metabolism, growth, cell division.
4.Ribosomes-are smallest membrane-bound organelles which are
composed of RNA(ribonucleic acid) and proteins. These are the
sites where protein synthesis takes place.
5.Chloroplasts- contain green coloured pigment substance called
chlorophyll which is needed for the process of photosynthesis.
6.Endoplasmic reticulum- is the largest organelle in the cell, is
located near the nucleus, and makes proteins and other
substances needed for the cell.
Rough endoplasmic reticulum= proteins
Smooth endoplasmic reticulum= other substances need (steroids,
lipids)
(synthesis, folding, modification, and transport of proteins)
SFMT=reti
7.Mitochondria(rion=singular)-are double-membraned
organelles.They provide energy by breaking down carbohydrates
and sugar molecules. They are known as powerhouses of the
cells.
Cellular respiration→Mitochondria
8.Golgi apparatus- is responsible for transporting, modifying, and
packing proteins and lipids into vesicles to deliver target
destinations.
9.Lysosomes- carry out digestion and removal of cellular waste.
As they have digestive enzymes (hydrolytic enzymes), they are
known as suicidal bags. They remove cellular waste by digesting
worn-out organelles, food, and foreign matter in the cells.
10.Vacuoles(storage)- perform storage of salts, minerals,
pigments, and proteins. These contain cell sap and water. They
also sustain turgor pressure. Store or Remove
11.Cytoplasm- gelatinous liquid inside the cell that is composed
of water, salt, and various organic molecules
Centrioles (only in animal cells), Cell wall, chloroplasts (only in
plant cell), Mitochondria (important)
Cell division
Cell division is the process by which a mother cell divides
into two or more daughter cells. In most prokaryotes (bacteria),
binary fission takes place. The other way is multiple fission.
Binary fission(asexual)
It is the primary method of reproduction in prokaryotes. In
the process of binary fission, the single DNA replicates. The size
of the cell becomes twice. And the nucleus divides into two parts,
each containing identical copies of the DNA.Gradually, the parent
cell is completely divided into two daughter cells.
In eukaryotes, there are two types of reproduction.
1.Mitosis
2.Meiosis
1. Mitosis
Mitosis is a type of cell division that results in two identical
daughter cells(diploid-2n). Mitosis produces somatic cells(body
cells). In which homologous chromosomes(same position,
structure, or value) are not paired.
Before starting mitosis, the replication of DNA occurs.
Interphase→ ▢the chromosomes are not clearly visible and
replicated.
Prophase→ ▢the nuclear membrane disappears
▢the chromosomes become visible.
Metaphase→ ▢the chromosomes are the most distinct
▢all of the chromosomes line up in the center
▢spindle fibers from centrioles attach the
chromosomes
Anaphase→ ▢the chromosomes are pulled to the centrioles.
Telophase→ ▢2 daughter cells are reproduced.
(cytokinesis) ▢The nuclear membrane reappears.
2.Meiosis
Meiosis is a type of cell division that results in four
daughter cells(haploid-n). Meiosis produces reproductive cells. In
meiosis, the chromosomes are paired.
A fertilized egg(zygote) is formed by the union of a sperm and
an ovum/egg, and has to be diploid. So, sperms and ovum having
haploid must be made by a special process.
As in mitosis, the replication of DNA occurs in meiosis.Meiosis
occurs in two stages: meiosis i, and meiosis ii.
Meiosis I
Interphase-the chromosomes are replicated
Prophase I
● the nucleus membrane disintegrates.
● DNA condenses into visible chromosomes.
● Matching pairs of chromosomes(homologous chromosomes)
exchange genetic material → crossing over
Metaphase I
● the homologous chromosomes align at the equatorial plate.
Anaphase I
● The homologous chromosomes are pulled towards the
opposite poles by the spindle fibers from the centrioles.
Telophase I
● the cytoplasm divides→ the cell is split in two non identical
daughter cells
● the nuclear membrane appears
Prophase II
● the nuclear membrane disintegrates again
● DNA condense into chromosomes
● no crossing over in this case
Metaphase II
● individual chromosomes line up (not homologous pairs)
Anaphase II
● the splitted chromatids are pulled towards the opposite
sides of the cell
Telophase II
● the nuclear membrane redevelops
● 4 non identical haploid cells(n) are formed
Chapter-2
Life Functions and Energy Intake
→ catabolic
→ Not just inhaling and
exhaling
→ break glucose to release
energy
→ occurs in mitochondria
C6H12O6 + 6O2 → 6CO2 + 6H2O+ Energy
In cellular respiration,
Polysaccharide (glucose) → monosaccharide
Step 1-Glycolysis
●Glucose is broken down
●Stored energy in a bond(electron) is produced. → loss of
electrons=oxidation of glucose
●6-carbon glucose is divided into 2 or 3-carbon
molecules(pyruvates).
●4ATP (net 2ATP), 2 NADH, 2 water molecules
●Take place in cytosol of cytoplasm
Step 2-Pyruvate oxidation
●Pyruvates are broken down into acetyl CoA
●𝐶𝑂2 2 molecules are produced
●2 Acetyl-CoA(2-carbon molecules) → Tricarboxylic Acid Cycle
or Citric Acid Cycle or Krebs cycle
●In mitochondria
Step 3-TCA cycle
●2 Acetyl-CoA is broken down again.
●Oxaloacetate (4-carbon) combines with broken Acetyl-CoA
●𝐶𝑂2 4 molecules are produced.
●6NADH, 2 FADH2, 4CO2 and 2ATP
●In mitochondria
In each step, the produced electrons are carried to the Electron
Transport Chain(final destination) by the electron carriers (NAD+
and FAD).
⛓️
Step 4-ETC-Electron Transport Chain
●Use electrons and produce ATP
●𝑂2→ final electron acceptor, and produce water.
●the place where most of the ATP are made
Fermentation-anaerobic respiration
-alternative method for converting energy
▢Lactic acid fermentation→Human (muscle pain)
▢Alcoholic fermentation → yeast
Yeast (single-celled eukaryotic organisms) → alcoholic
fermentation
-glycolysis
⁕ethanol (alcohol) and carbon dioxide
⁕ 2 ATP
Lactic fermentation
-During strenuous exercises, energy is used faster and oxygen
cannot be delivered to the muscle enough→lactic fermentation
-glycolysis
⁕lactate (muscle fatigue)
⁕2 ATP
Photosynthesis → anabolic
Cells need a source of energy to function. Most organisms
are consumers. They eat other organisms, and obtain energy
from food. Producers, mostly plants, produce their own food by
photosynthesis.
•Carbon dioxide enters the leaves through the stomata.
•Water is absorbed by the roots.
•When light energy enters the cell through the cell membrane,
Carbon dioxide and water react in chloroplasts.
•Photosynthesis produces glucose and oxygen.→Glucose is the
source of food for plants.
•The glucose is stored as starch in plants.
•The oxygen leaves the leaf through the stomata.
Electron Transport Chain → Calvin Cycle → Glucose
1.Light reaction-ETC
-convert light energy to the chemical energy (ATP and NADPH)
-splits 𝐻2𝑂 and release 𝑂2 into the atmosphere
-light energy → chlorophyll becomes excited (wanna lose e-)
-ETC → ATP
-within the thylakoid membrane
●Photosystem II (discovered later but takes place first)
●Photosystem I
2.Calvin cycle
●Rubisco enzymes → RuBP+Carbon dioxide
-takes place in stroma
-light-independent
Two types of chemical reactions:
1.Exergonic(Exothermic) reaction→energy is released
→spontaneous
2.Endergonic(Endothermic) reaction → energy is absorbed
→non-spontaneous
DNA and Chromosomes
Nucleus → Chromosomes → DNA → Genes
DNA is made up of 4 chemical bases
(nucleotides):
(1)Adenine
(2)Thymine
(3)Cytosine
(4)Guanine
DNA (double helix)
●carry genetic codes
●can replicate itself
Structure
▢two strands
▢Backbone made of sugar(deoxyribose) and phosphate
Genes- hereditary units/ segment of DNA ← inherited from
parents
Chromosomes - mostly thread-like structures
Homologous-same structure, different functions
Analogous- different structures, same function
Proteins → make physical traits/phenotype (e.g. eye color)
Different cells→ different proteins
Proteins are enzymes that faster the reactions
Central dogma of biology/
Central dogma of molecular biology/
Protein Synthesis
Transcription → in the nucleus
Translation → in the ribosomes (cytoplasm)
Chromosomes
-in reproductive cells
-DNA + proteins(histones)
-normal cells → 46 chromosomes / reproductive cells → 23
chromosomes
kinetochore→ place where
spindle fibers attach
Chromosomes → Genes ← made up of DNA
In humans, 23 pairs of chromosomes
22 pairs (autosomes) + 1 pair (sex chromosome) = karyotype
Male- XY karyotype
Female- XX karyotype
Mutation
-change in the DNA sequence ← DNA replication error during
cell division
-errors in building proteins (can be caused by environmental
acts like smoking, radiation, etc.)
Good → adaptation and evolution
Bad →can cause diseases(cancer), but sometimes no impact on
health
●germline mutation → in eggs and sperms → can be passed on
to offsprings
●somatic mutation → in body cells → cannot be passed on
Chromosome mutation→ large-scale mutation (more dangerous)
-affects growth, development, and functions of the body systems
Gene mutation → small-scale
-one or few nucleotides are affected
-result in an altered sequence of
amino acids
Alleles and Traits
Alleles
-different versions of genes
-on the gene loci of the homologous chromosome
-two alleles in a gene
-genotype
-can be visualized through DNA testing
E.g. blood type
●Two types of alleles
1. Dominant
2. Recessive
AA-homozygous dominant
aa-homozygous recessive
Aa-heterozygous (all dominant)
Traits
-genetically determined characteristics
-determined by genes (alleles)
-occur individual
-can be influenced by the environment
-phenotype
-visible by naked eyes
Assortment of Alleles
-crossing over→ inner chromatids are linked and changed
Blood types
A,B → dominant
O → recessive
Environmental Altering of Traits
-some traits (like blood type) are the direct result from the
alleles you inherit from your parents can’t be changed
-others= alleles + environmental factors
Expression of Traits
-environmental factors (e.g. temperature) influence the
expression of genetic traits
⁕Gene regulation
→ gene turned on (expressed) and turned off (not expressed)
→important part of normal development
→respond to the environmental changes
→switch on/off to control when proteins are made
→control increasing or decreasing amount of proteins
Simple Inheritance
Combination of alleles for gene → genotype
Physical traits → phenotype
Genotype determines phenotype.
A gene has two alleles represented
by a capital letter and a small letter.
Eye color
●Brown → dominant
●Blue → Recessive
Blood type
●A,B → dominant
●O → recessive
●Healthy → dominant (homozygous dominant)
●Unhealthy → recessive (homozygous recessive)
●Carrier → heterozygous
Probability
Punnett square
Pedigree chart
-to trace the inheritance trait through the generations of the
family
-to learn genetic disorders (e.g. color blindness)
Types of dominance
●Complete dominance → one of the two traits appears
●Incomplete dominance → a new mixed trait appears
→ no lower case
→ heterozygous
●Codominance → spotted of both trait
→ no lower case
→ heterozygous
Types of dominance: For VA
✨
Scientific Method
-to get the cause-and-effect relationships
7-steps (Hypothesis)
1.Ask a question (about sth that you observe)
2.Perform research (collect data)
3.Establish a hypothesis (educated guess to answer the
question)
4.Make an experiment (test to the hypothesis)
5.Make an observation (make sure all conditions are
the same, repeat the experiment to make sure
the results are accurate)
6.Draw conclusion (analyze and conclude)
7.Report (share to others)
Types of variables
-Independent variable → that you change in the experiment(if
one more, it’ll be difficult)
-Dependent variable → that is affected by the independent
variable
-controlled variable → that is kept constant to get accurate
results
Control Groups
●A single experiment may include multiple experimental groups,
which may all be compared against the control group.
-ensure that your experiment actually works
-are extremely useful where the experimental conditions are
complex and difficult to isolate
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Placebo concurrent control: one group is given the treatment, the other a
placebo (“sugar pill”).
Dose-comparison concurrent control: two different doses are
administered, a different one to each group.
No treatment concurrent control: one group is given the treatment, the
other group is given nothing.
Active treatment concurrent control: one group is given the treatment,
the other group is given an existing therapy that is known to be effective.
Historical control: only one physical group exists experimentally (the
experimental group). The control group is compiled from historical data.
Evolutionary Relationships
Common ancestry
-the theory that related organisms evolved from a shared
ancestor
Evolution
-is the change in characteristics of living things over time
-by mutation, genetic variation
●Microevolution - small changes → short time → many times of
microevolution (over millions of years) → macro
●Macroevolution - large changes → long time
All living things → common ancestor
Evidence of Evolution
⁕Anatomy
⁕Ancestor
⁕Molecular Biology
⁕Biogeography → unique features ← in different geographical
locations
⁕Fossils
⁕Direct observation
Short lifespan → greater population
E.g. the emergence of drug-resistant bacteria and
pesticide-resistant insects
Cladograms
-used shared characteristics to show how organisms are related
Here,
the tortoise is the outgroup
House cat is the only one that shares most characteristics.
Evolution by Natural Selection
Natural selection → natural factors (nature) → affect species ←
more able to survive and reproduce than others
survival of the fittest
Natural selection → drives Evolution
Artificial selection → man-made improvement to organisms ←
more benefits (able to survive)
Farmers and Animal breeders
Selection pressures (occur first)
Selection pressures → cause Natural Selection
Limited resources
●Food sources
●Clean water
●Living space
●Suitable mates
Environmental threats
●Predators
●Human activity
●Disease
Requirements for Selection
VISTA
-Variation in traits
-Inheritance
-Selection
-Time and Adaptation
Differential survivability
-survive and reproduce
Different survivability → natural selection
Evolutionary Change
Adaptation
-adjust to the environment and situation
-Able to better survive in a unique environment
-in both plants and animals
-natural selections lead to adaptation
Animals
●Finches on the Galapagos island
-change beak shape according to available food
Plants
●Roses with thorns
-have thorns to prevent being destroyed
Three types of Adaptation
●Structural adaptation
●Behavioral adaptation
●Physiological adaptation and Co-adaptation
——Structural adaptation——
-large ears → keep bodies cool
-thorns → protect from predators
——Behavioral adaptation——
-hibernation
-Venus fly-trap
——Physiological adaptation——
-efficient kidneys in desert animals
-the presence of toxins in plants
-homeostasis ( a state of balance among all the body systems
needed for the body to survive and function correctly)
Like sweating
——Co-adaptation——
-flowers and bees
-people and trees
—–Speciation—–
-adaptation → a new species evolve → speciation
Galapagos→ Finches
Moths
Long-neck giraffes
Ecosystem
-interaction between biotic factors and abiotic factors
-energy is constantly cycling through ecosystems
Producers
-sun’s radiant energy → chemical energy
Primary consumers
-herbivores
-consume producers (plants)
Secondary consumers
-carnivores
-consume herbivores
Omnivores
-consume both plants and animals
Decomposers
-break down dead organisms
Just 10% to other levels
Matter in Ecosystems
Food Chain vs Food Web
Food chain→ up to 5 links
Food webs→ complex
The end of the arrow → being consumed
The top of the arrow → consumer
Trophic Cascade
-a phenomenon of changing a trophic level
-can control entire ecosystems
●top-down cascade → reducing top level consumer/predators →
increasing preys → decline of producers
●bottom-up cascade → insufficient nutrients → decrease of
producers → decline of consumers
●subsidy cascade →
Capacity for change
-maximum number of organisms that a particular environment
can support over time-with graphs
-resources increases → carrying capacity increases →
population increases
Limiting factors
-to prevent overpopulation
Abiotic factor→non-living
Biotic→living
1. Competitors/ limited resources (survivability→ depends on
population)
2. Disease and parasites (depends on population)
3. Weather (indirectly dependent on population)
4. Available habitat (habitats)
5. Predators (affects population)
Fires (by man) → remove invasive species in forest
Invasive species → non-native species that cause imbalance in
community
Keystone species → native species
Relationships in Ecosystems
●Predator-prey relationship (predator feeds on prey)
-prey increases → predator increases
-prey decreases → predator decreases
-predation → can also be limiting factor
●Symbiosis
-affects other species’ survivability
-close and long-term relationship between
different species
Parasitism → parasite (benefit) + host (harm)
Mutualism → both species (benefit)
Commensalism → one species (benefit) + other (neutral)
Disruption of Ecosystems
-Conditions in ecosystem → no constant ← affected by some
factors (flood, fire)
Disturber
Flooding → habitats
Habitat destruction → by human actions (mining, drilling)
Desertification → by deforestation (human activities)
Invasive species
Recovery after being disturbed
-succession
Extinction
-certain species no longer exist
-caused by both natural processes and human activities
e.g. hunting, urbanization, destruction of forests.
Chapter-6
The Human Body and Health
Homeostasis
-external factors→ internal stimuli
-maintenance of internal balance
●constant body temperature → 37℃ (98.6℉)
Positive feedback (excessive)
-need fast adaptation
-increases (continue) the stimulus
For example,
Pepsinogen → pepsin → triggers a process → convert more
pepsinogen
During childbirth → oxytocin → speeds up the muscle
contractions →more and more oxytocin → baby born
Negative feedback
-doesn’t need fast recovery
-reduces the stimulus to keep in balance
-happens when body syst
Long Term negative feedback → positive
A Homeostatic Feedback Loop
Receptor → organs
Control center →send stimulus to turn back to normal state(set
point) brain, spinal cord
Effector → turns back to normal state
Effects of External Environments
Homeostasis → also respond external environment
Heat → sweating → keeping body cool → homeostasis
Cool → movement, muscle shivering → warm → homeostasis
●Hypothermia → fail to respond cool → cold body temperature
●Hyperthermia → fail to respond heat → hot body temperature
Nutrition
-eating a healthy and balanced diet
40 different kinds of nutrients in food
7 major groups
6 major nutrients
Macronutrients (large amount is needed)
●Carbohydrates (main energy source)
●Proteins (harm kidneys)
●Fats
●Water
Micronutrients (a small amount is needed)
●Vitamins
●Minerals
●Dietary fiber
Olive oil is the best
Water → 0 cal
▢Carbohydrates
-provide energy
-from grains, rice, and noodles, fruit, dairy products
▢Proteins
-build and repair tissue
-meat, fish, eggs, seafood, dairy products
-excessive amount of proteins → kidneys
▢Fats
-provide backup energy
-prevent heat loss in extreme cold weather, and protect organs
shock
-meat, fish, dairy products, nuts, seeds, oil
-lead to obesity
●unsaturated fats → good
●saturated fats → bad
▢Vitamins
-maintain optimal health
-maintain healthy skin and hair, build bones and releasing and
utilizing energy from foods
▢Minerals
-maintain optimal health
-regulation of fluid balance, muscle contraction, and
transmission of nerve impulses
-calcium, magnesium, iron
▢Dietary fiber
-stabilize blood sugar, promote gastrointestinal health, and
prevent constipation
-in indigestible part found in plant
▢Water
-most abundant
-regulation of body temperature
-production of liquid
-transportation of nutrients
-removal of waste products
▢Bacteria (another source of nutrients)
-beneficial bacteria in digestive system
-symbiotic bacteria
●break down food
●make Vitamins B and K (essential)
Vitamin D → most important overall
Water → nutrient
Carbohydrates → carbs (sugar molecules)
Nutrition Concepts
-well-balanced diet → essential
-D deficiency → lower bone density
-C deficiency → scurvy
-Iron → anemia (not having enough RBCs)
-Excessive proteins → harm kidneys
Energy for bodies unit -calories (cal)
Fat 1g= 9 cal
Protein 1g= 4 cal
Carb 1g= 4 cal
Both deficiency and excess → problems
Diseases and Pathogens
Diseases
-affect the normal function of the human body
-include minor injuries like cuts
Pathogen
-microorganisms or virus that causes, or can cause diseases to
hosts
-living thing
-infectious diseases caused by pathogens
●bacteria
●virus
●fungi
●worms
●protozoa
Facultative pathogens → can replicate without host
Obligate pathogens → cannot replicate without host (e.g.
viruses)
Transmission of pathogens
• Nose, mouth, or eyes to hands to others
• Hands to food
• Food to hands to food
• Infected child to hands to other children
• Animals to people
●Droplet infection (nose or mouth)
-cough or sneeze → droplets
(including bacteria or viruses) → others
•Flu
•Tuberculosis
•Common cold
●Direct contact (skin)
-skin-to-skin contact
•Athlete’s foot
•Genital herpes
●Contaminated food and water (mouth)
-eating raw or undercooked food, and drinking water with dirts
•water → cholera and amoebic dysentery
•food → Salmonella
●By body fluids (blood, spit)
-pathogens enter → blood
-cuts and scratches, and needle punctures
•HIV/ AIDS
•Hepatitis
●Vectors (carrier)
-animals (carrier) spread disease-causing organisms
-mosquitoes and houseflies
•Malaria
•Dysentery
•West Nile virus
Prevention of Disease
-sanitation
-adopting healthy behaviors
●washing hands often
●covering while coughing and sneezing
●careful preparation of food before you eat
Virus vs Bacteria
Bacteria
→ free-living cells (can live both inside and outside a body)
→ can be treated with antibiotics
→ sometimes contagious
Virus
→ non-living collection of molecules (can’t live and replicate
without host)
→ can’t be treated with antibiotics
→ contagious
Vaccines
-enables to develop immunity without suffering from the actual
disease that the vaccine prevents
-contain weakened or inactive parts of antigens
-introduce safe amounts of antigens to the body
Antigens and Antibodies
Antigens → provokes production of antibodies
Antigens
-foreign particles that enter the body
-include bacteria, virus, fungi, toxins, venom
Antibodies
-soldiers in the body’s defense system
-each antibody is trained to recognize specific antigen
Body systems
https://biologydictionary.net/body-systems/