Biology Final Review
Chromosomes
• Chromosomes are DNA & its
associated proteins.
 We have 46 chromosomes or 23
pairs of chromosomes.
• In a prokaryotic cell, it is the
main ring of DNA.
Autosomes vs. Sex Chromosomes
•
Autosomes are any chromosomes that are
not directly involved in determining the
sex of an individual.
 We have 22 pairs.
•
Sex chromosomes contain genes that will
determine the sex of the individual.
 We have one pair.
 Females are XX.
 Males are XY.
Autosomes vs. Sex Chromosomes
Gametes
• Gametes are an organism’s
reproductive cells.
 Female’s gametes are eggs or ova.
 Male’s gametes are sperm.
Haploid vs. Diploid
• Haploid refers to a cell (gamete) that
contains only 1 set of chromosomes.
 It is represented by “n.”
• Diploid refers to a somatic or body
cell that contains 2 sets of
chromosomes.
 It is represented by “2n.”
Define Haploid
• Describes a
cell, nucleus or
organism that
has only one
set of unpaired
chromosomes.
Define Diploid
• A cell that contains
2 sets of haploid
chromosomes
• Body or somatic
cells contain a
diploid number of
chromosomes.
Karyotype
• A picture of the chromosomes found in an
individual’s cells at metaphase of mitosis
& arranged in homologous pairs & in order
of diminishing size with the sex
chromosomes last.
• Down’s Syndrome
is trisomy 21.
Parts of a Microscope
Microscopes and Magnification
• Ocular lens x
objective lens = total
magnification
• Magnification –
making image appear
larger
• Resolution – clarity
of image
Cell Theory
• All living things are made of cells.
• Cells are the basic units of
structure and function in
organisms.
• All cells come from existing cells.
Prokaryote vs. Eukaryote
• Prokaryote





No nucleus
No membrane bound organelles
Circular DNA
Relatively small
Reproduce quickly (20 min.)
 Examples: Bacteria
Prokaryote vs. Eukaryote
• Eukaryote





Nucleus
Many membrane bound organelles
Linear DNA
Relatively large
Reproduce slowly (24+ hours)
 Examples: Plants, animals, fungi &
protists
Cell Parts & Functions
•
Cell membrane
 Controls what enters & leaves a cell;
separates & protects the cell from the
environment.
•
Nucleus
 Contains the DNA in eukaryotic cells;
controls cellular activities.
•
Vacuole
 Membrane bound sac that stores water, may
also contain ions, nutrients & waste.
Cell Parts & Functions
•
Chloroplast
 Organelle that uses light energy to make
carbohydrates from CO2 & H2O.
•
Cytoplasm
 Region of the cell within the membrane that
includes the fluid, the cytoskeleton and all of
the organelles except the nucleus.
•
DNA
 Material that contains the information that
determines hereditary characteristics.
Cell Parts & Functions
•
Ribosomes
 Organelle composed of RNA & protein; site
of protein synthesis.
•
Mitochondrion
 Cell organelle surrounded by 2 membranes &
is the site of cellular respiration, which
produces ATP.
•
Cell Wall
 Rigid structure that surrounds the cell
membrane & provides support to the cell.
5 Stages of the Cell Cycle
5 Stages of the Cell Cycle
• The first 3 stages are collectively
called interphase. (90% of a cell’s
life is spent here.)
1. First growth (G1) phase
 Cell grows rapidly & carries out
routine functions. (Major portion of a
cell’s life is spent here.)
5 Stages of the Cell Cycle
2. Synthesis (S) phase
 Cell’s DNA is copied.
 Each chromosome consists of 2 chromatids
attached at the centromere.
3. Second growth (G2) phase
 Preparations are made for the nucleus to
divide.
 Microtubules are rearranged.
 Organelles are manufactured or reproduced.
5 Stages of the Cell Cycle
4. Mitosis
 The nucleus of a cell divides into 2
nuclei each with the same # and kinds
of chromosomes as the original cell.
5. Cytokinesis
 The cytoplasm divides and 2 new cells
are formed.
3 Checkpoints
• A checkpoint is an inspection point
at which feedback signals from the
cell can trigger the next phase of the
cell cycle or delay it.
1. Cell Growth (G1) checkpoint at the end
of the G1 phase
 Makes the decision of whether or not a
cell will divide.
3 Checkpoints
2. DNA synthesis (G2) checkpoint at the
end of the G2 phase
 DNA replication is checked by DNA
repair enzymes.
3. Mitosis checkpoint at the end of
mitosis
 Triggers the exit from mitosis
4 Phases of Mitosis
1. Prophase
 Chromosomes become
visible.
 Nuclear envelope
dissolves.
 The spindle forms.
 In animal cells, the
centrioles move to
opposite poles and the
spindle forms between
them.
4 Phases of Mitosis
2. Metaphase
 Chromosomes
move to the center
of the cell & line
up along the
equator.
 Spindle fibers link
the chromatids of
each chromosome
to opposite poles.
4 Phases of Mitosis
3. Anaphase
 Centromeres divide.
 The 2 chromatids
(now called
chromosomes)
move toward
opposite poles as the
spindle fibers
attached to them
shorten.
4 Phases of Mitosis
4. Telophase
 A nuclear envelope
forms around the
chromosomes at
each pole.
 The chromosomes
uncoil and return to
chromatin form.
 The spindle
dissolves.
 Cytokinesis begins.
Cytokinesis
•
•
•
•
Division of the cytoplasm of a cell
Follows the division of the cell’s nucleus by
mitosis or meiosis
Cytokinesis in animal cells occurs when a
belt of protein threads pinches the cell
membrane in half.
Cytokinesis in plant cells occurs when
vesicles from the Golgi apparatus fuse to
form a cell plate.
Cytokinesis
•
Cytokinesis in
animal cells
Cytokinesis in
plant cells
Define Meiosis
• A process in cell division during which the number
of chromosomes decreases to half the original
number by two divisions of the nucleus, which
results in the production of sex cells (gametes or
spores)
What are the 4 things that give rise
to variation within a species?
• Independent assortment
• Crossing-over
• Random fertilization
• Mutations
Differentiate between
spermatogenesis & oogenesis.
• Spermatogenesis
2 nuclear
divisions in which
the cytoplasm is
divided equally
4 sperm
produced from
parent cell
Differentiate between
spermatogenesis & oogenesis.
• Oogenesis
First nuclear division,
cytoplasm divides
unequally – one of
the cells gets nearly
all of the cytoplasm
This cell will
ultimately give rise to
one egg – the 3 polar
bodies will die
Complete the following diagrams
2n
2n
2n
Process: Mitosis
Process: Meiosis
Compare Mitosis and Meiosis
What are the 3 different ways
asexual reproduction occurs?
• In asexual reproduction, a single parent
passes exact copies of all of its DNA to its
offspring.
• Fission
• Fragmentation
• Budding
Nondisjunction
• One or more chromosomes fail to separate
properly during meiosis.
• One gamete ends up receiving both
chromosomes and the other gamete receives
none.
• Trisomy occurs when the gamete w/ both
chromosomes fuses w/ a normal gamete,
resulting in an offspring w/ 3 copies of a
chromosome instead of 2.
Diffusion vs. Osmosis
•
Diffusion
 The movement of particles from regions of
higher concentration to regions of lower
concentration.
 Ex: perfume spreading across a room.
•
Osmosis
 The diffusion of water from an area of high
concentration to an area of low concentration
across a membrane.
 Ex: Getting thirstier when you drink salt
water.
Passive vs. Active Transport
• Passive Transport
 Does not require energy.
 Movement down the concentration
gradient.
 Examples:
 Diffusion
 Osmosis
 Facilitated diffusion
Passive vs. Active Transport
•
Active Transport
 Requires energy.
 Movement against the concentration gradient.
 Examples:
 Sodium-potassium pump
 Endocytosis
 Phagocytosis
 Pinocytosis
 Exocytosis
Fig. 5-1a
Carbohydrate of
glycoprotein
Glycoprotein
Glycolipid
Integrin
Phospholipid
Microfilaments
of cytoskeleton
Cholesterol
ATP
• The energy “currency” of the cell.
• An organic molecule that acts as the
main energy source for cell processes
• Composed of a nitrogen base, a sugar
& 3 phosphate groups.
• The energy is stored in the phosphate
bonds.
• Powers metabolism.
Photosynthesis
• Process by which plants, algae &
some bacteria use sunlight, CO2 &
H2O to produce carbohydrates & O2.
• Takes place in the chloroplast
• Main pigment is chlorophyll.
• Reactants are CO2 and H2O
• End products are glucose & O2
Photosynthesis
• Stage 1
 Consists of the absorption of light
energy which excites the electrons in
chlorophyll.
 The electrons enter the ETC (electron
transport chain).
 Water is split to produce O2, H+, and
the electrons to replace those lost by the
chlorophyll molecules.
Photosynthesis
• Stage 2
 The conversion of light energy into
chemical energy that is temporarily
stored in ATP and NADPH.
 The energy from ATP and NADPH
will be used to power the third stage.
Photosynthesis
• Stage 3
 CO2 fixation occurs
 Inorganic CO2 is fixed into organic
compounds (sugars).
Cellular Respiration
• Process by which cells produce
energy from carbohydrates; O2
combines w/ glucose to form H2O &
CO2.
• Takes place in the mitochondrion.
• Reactants are glucose and oxygen.
• Products are carbon dioxide & water.
Aerobic Respiration vs.
Anaerobic Respiration
•
Aerobic Respiration
 Requires oxygen.
 Produces much more ATP (38 net ATP)
•
Anaerobic Respiration
 Does not require oxygen.
 Regenerates NAD+ so that gylcolysis can
continue.
 (2 net ATP from glycolysis)
Aerobic Respiration
• Stage 1 – Glycolysis takes place in
the cytoplasm.
 Does not require oxygen.
 Glucose is broken down to 2 pyruvate
molecules
 Produces 2 net ATP and 2 NADH
• Stage 2 – Bridge reaction carries
pyruvates into the mitochondrion.
 2 CO2 and 2 NADH are produced
Aerobic Respiration
• Stage 3 – Krebs Cycle occurs in the
matrix of the mitochondrion
 In the presence of oxygen.
 In two turns of the Krebs Cycle:




4 CO2 are produced
6 NADH are produced
2 ATP are produced
2 FADH2 are produced.
Aerobic Respiration
• Stage 4 – Electron Transport Chain
occurs in the inner membrane of the
mitochondrion
 In the presence of oxygen.
 34 net ATP produced




2NADH from glycolysis = 6ATP
2 NADH from bridge reaction = 6 ATP
6 NADH from Krebs cycle = 18 ATP
2 FADH2 from Krebs cycle = 4ATP
Anaerobic Respiration or
Fermentation
• Alcoholic Fermentation
 Occurs in the absence of oxygen
 Occurs in yeast and some bacteria
 Produces:
 Ethyl alcohol
 Carbon dioxide
 Regenerates NAD+ so glycolysis can
continue
Anaerobic Respiration or
Fermentation
• Lactic Acid Fermentation
 Occurs in the absence of oxygen
 Occurs in the muscle tissue of animals
& in lactic acid bacteria
 Produces:
 Lactic acid
 Regenerates NAD+ so glycolysis can
continue
Atom and Its Parts
• An atom is the smallest unit of an
element that maintains the properties
of that element.
 Nucleus contains:
 Proton (+)
 Neutron (Neutral)
 Electron cloud
 Electron (–)
Covalent vs. Ionic Bonds
• Covalent Bond
 Bond formed when atoms share pairs of
electrons.
• Ionic Bond
 Bond formed by the attraction between
oppositely charged ions.
Covalent vs. Ionic Bonds
Molecules and Polar Molecules
• Molecule
 A group of atoms held together by
covalent bonds.
• Polar Molecule
 Shares its electrons unequally and
therefore has partially positive and
negative ends, or poles.
 Water is a polar molecule.
Molecules and Polar Molecules
Solvents
• Solvent
 A substance, usually a liquid,
capable of dissolving another
substance.
• Universal Solvent
 Water.
pH Scale and Acids & Bases
•
pH Scale ranges from 0 - 14
 Acid


A compound that forms hydrogen ions (H+) in water.
Its pH is 0 to less than 7. (0 to < 7)
 Base


A compound that forms hydroxide ions (OH-) in water.
Its pH is greater than 7 to 14. (>7 to 14)
 Neutral

Substances that have a pH of 7.
Organic Macromolecules
•
Organic macromolecules:
 Contain carbon atoms that are covalently
bonded to other elements – typically
hydrogen, oxygen and other carbon atoms.
 4 principal classes of organic compounds
found in living things are:




Carbohydrates
Lipids
Proteins
Nucleic acids
Organic Macromolecules
•
Carbohydrates – organic compounds made of
carbon, hydrogen and oxygen in a 1:2:1 ratio.
 Monomers are monosaccharides.

Ex: Glucose and fructose
 Polymers are polysaccharides.

Ex: Starches, potatoes, paper, crab shells
 Functions



Stores energy.
Makes up cell walls in plants and fungi.
Makes up exoskeleton in some animals.
Organic Macromolecules
•
Lipids are nonpolar molecules that are
insoluble in water & include fats,
phospholipids, steroids and waxes.
 Monomers are glycerol & fatty acids
 Polymer examples
 Butter & oil
 All membranes
 Cholesterol and Steroids
 Functions
 Stores energy
 Makes up cell membranes
 Acts as chemical messengers
Organic Macromolecules
•
Proteins
 Monomers are amino acids
 Polymer examples


Hemoglobin and antibodies
Muscle, hair and nails
 Functions



Hemoglobin carries oxygen and antibodies help
defend against infection.
Make up tissues that support body structures and
provide movement
Speed up chemical reactions (enzymes)
Organic Macromolecules
•
Nucleic acids
 Monomers are nucleotides
 Polymer examples
 DNA
 RNA
 Functions
 Controls cellular activities
 Stores hereditary information
 Plays key role in the manufacture of
proteins
Catalyst vs. Enzyme
• Catalyst
 Speeds up chemical reactions by
lowering the activation energy.
• Enzyme
 Specialized protein that acts as an
organic catalyst.
Test Indicators & Positive Results
•
Benedict’s solution
 Tests for simple sugars – blue color changes
to red, orange, yellow, green.
•
Lugol’s iodine
 Tests for starch – reddish–orange iodine turns
blue-black or black.
•
Biuret solution
 Tests for protein – blue turns purple.
•
BTB (Bromthymol blue)
 Tests for CO2 – blue turns green, or yellow.