Advanced Biology
Semester 1 Review Part II
Chapters 5 - 9
Chapter 5 The Working Cell
 Things to know and Be Able To Do






Types of energy
Laws of Thermodynamics
ATP
Enzymes
Membranes
Cellular Transport
 Review notes, study guides, and labs
Energy is the Capacity to
Perform Work
 Kinetic Energy: Energy that is actually
doing work
 Heat and Light
 Potential Energy: Stored energy due to
location or arrangement of matter
 Chemical energy is a form of potential
energy due to the arrangement of atoms in
a molecule due to the chemical bonds
Laws of Thermodynamics
 1st law: Energy can not be created or destroyed.
It can be transformed from one form to another.
 Cells do not make energy or consume energy, they
transform energy from one form to another.
 From the chemical energy of glucose to the chemical
energy of ATP
 2nd Law: Energy transformations reduce the
order of the universe
 Energy transformations are not 100% efficient
 In all energy transformations some energy is lost in the
form of heat.
Chemical Reactions Store or
Release Energy
 Exergonic reactions release energy by breaking
bonds.
 Endergonic reactions store energy by forming new
bonds
 Energy Coupling: Cells use energy released by
exergonic reactions to power essential endergonic
reactions.
 Most energy released by exergonic reactions is stored in
the bonds of ATP
 ATP molecules shuttle this energy to places where it is
required for essential endergonic reactions
Enzymes
 Enzymes are proteins
 Enzymes speed up chemical reactions by lowering
the activation energy of the reaction but are not
consumed in the chemical reaction (biological
catalysts)
 Enzymes are specific to the reactions they
catalyze
 Active site: Region of the protein that binds to the
substrate
 Substrate: a reactant in the chemical reaction that the
enzyme acts on, must fit in the active site
Factors Affecting Enzyme
Activity
 pH, Temperature, and salinity can denature an
enzyme
 Inhibitors can block an enzymes active site
 Competitive: Sit in the active site and prevent substrate
from entering the active site
 Noncompetitive: Bind to the enzyme outside of the
active site, but cause the protein to change its overall
shape, thus altering the active site.
 Reversible: When inhibitors bind to the enzyme by
weak H-bonds, can be easily be undone
 Irreversible: When inhibitors bind to the enzyme with
strong covalent bonds
Membranes
 Organize cellular activities
 Phospholipid Bilayer
 Two layers of phospholipid molecules
 Polar heads face away from each other, nonpolar tails
face towards each other
 Allow small, nonpolar molecules to diffuse through the
membrane and into the cell
 Proteins
 Embedded in the phospholipid bilayer
 Many functions depending on the type of protein
 Enzymes, receptors, connnect cell to its surroundings,
transport molecules into and out of the cell
 Carbohydrates
 Cell ID tags to allow the cell to be recognized by other
cells that are part of the same organism
Cellular Transport
 Diffusion: the movement of molecules from
areas where they are highly concentrated
to areas where they are less concentrated
 Results from random motion of molecules
 Requires no work
 Molecules diffuse down their concentration
gradient, unaffected by the concentration of
other molecules
 Passive Transport: The diffusion of
molecules across the membrane of a cell
Osmosis
 The diffusion of water across a selectively
permeable membrane
 Water can diffuse easily across a biological membrane
 Solute molecules can not diffuse across biological
membrane
 Water will diffuse until the concentration of water is
equal on both sides
 Hypertonic: Solutions with a high solute
concentration compared to another solution
 Hypotonic: Solutions with a low solute
concentration compared to another solution
 Water will move by osmosis from hypotonic
regions to hypertonic regions
 In Hypotonic Solutions
Osmoregulation
 Animal cells will lyse
 Plant cells become turgid but do not lyse, due to rigid cell
wall
 In Hypertonic Solutions
 Animal cells will shrivel
 Plant cell membranes will shrivel, cell wall will not change
dimensions.
 Osmoregulation: Organisms must use energy to
control water loss or gain in their cells due to
osmosis. They can not stop osmosis.
 Example: Freshwater fish pee constantly
Saltwater fish constantly drink, and
concentrate urine in their tissues
Facilitated Diffusion and Active Transport
 Facilitated diffusion is the movement of
molecules across a membrane by diffusion
through transport proteins
 Transport proteins form channels that allow
large, polar, or charged molecules to cross the
cell membrane
 Active Transport uses energy and transport
proteins to move molecules against their
concentration gradient
 Active transport like all cellular work is powered
by ATP
Chapter 6
 Things to Know and Be Able to Do:
 Overall chemical equation for aerobic cellular
respiration
 Inputs and outputs for all stages of cellular
respiration
 Location of each of the stages
 Fermentation
 Review Chapter 6 notes, labs, and review
packets
Aerobic Cellular Respiration
 C6H12O6 + 6O2 ---> 6CO2 + 6H2O + 36-38 ATP
 Glucose is broken down into Carbon dioxide and
water
 Requires oxygen
 Produces between 36 and 38 ATP molecules
 Has three major steps
 Glycolysis
 Kreb’s Cycle
 Electron Transport Chain and Chemiosmosis
Glycolysis
 First stage of Aerobic cellular respiration
AND fermentation
 Takes place in the cytoplasm of all cells
 2 molecules of pyruvic acid result from the
splitting of glucose
 2 molecules of NADH shuttle electrons and
hydrogen ions to the Electron Transport Chain
 2 molecules of ATP are made directly during
glycolysis by substrate level phosphorylation
Chemical Grooming
 Intermediate step between Glycolysis and
the Krebs Cycle
 2 molecules of CO2 are produced; 1 from
each pyruvic acid
 2 molecules of NADH shuttle electrons and
hydrogen ions to the Electron Transport
Chain from the break down of pyruvic acid;
1 NADH from each pyruvic acid molecule
 2 molecules of Acetyl CoA are formed from
the break down of pyruvic acid
 No ATP is made directly in this stage
Kreb’s Cycle
 Second major step of aerobic cellular respiration
 Occurs in the matrix of the mitochondria in
eukaryotic cells
 4 molecules of carbon dioxide result from the
break down of the Acetyl CoA; 2 molecules from
each Acetyl CoA
 6 NADH and 2 FADH2 shuttle electrons from the
breakdown of Acetyl CoA to the ETC; 3 NADH and
1 FADH2 from each Acetyl CoA
 2 ATP are made directly by substrate level
phosphorylation; 1 ATP from each Acetyl CoA
Electron Transport Chain and
Chemiosmosis
 Final stage of aerobic Cellular respiration
 Takes place along a chain of protein
molecules embedded in the inner
mitochondrial membrane
 Produces about 34 molecules of ATP using
the NADH and FADH2 produced in previous
stages; 3 ATP per NADH and 2 ATP per
FADH2
Electron Transport Chain and
Chemiosmosis (continued)
 Electrons from NADH and FADH2 move down the
Electron Transport Chain by redox reactions and
release energy.
 Oxygen is the last electron acceptor in the chain
 The released energy is used to actively transport
H+ across the inner mitochondrial membrane from
the matrix to the intermembrane space
 H+ flows back into the matrix through ATP
synthase which powers the phosphorylation of
ADP to ATP
Alcoholic and Lactic Acid Fermentation
 Fermentation is an alternative to aerobic respiration when
oxygen supplies are limited or not present.
 Both use glycolysis to make ATP
 Alcoholic Fermentation
 Breaks glucose down in to pyruvic acid
 Converts pyruvic acid into ethanol and CO2 to recycle NAD+
 Produces 2 ATP per glucose
 Common in yeast and bacteria, used to make beer and wine
 Lactic Acid Fermentation
 Breaks glucose down in to pyruvic acid
 Converts pyruvic acid into lactic acid to recycle NAD+
 Produces 2 ATP per glucose
 Occurs in muscle cells, causes muscle soreness
Chapter 7
 Things to know and be able to do:
 The overall equation and purpose of
photosynthesis
 The inputs and outputs of each stage of
Photosynthesis
 The location of each of these stages
 Review all chapter 7 notes, labs, and review
packets
Photosynthesis
 CO2 + H2O + light ---> C6H12O6 + O2
 Organisms that can photosynthesize are called
autotrophs or producers
 Photosynthesis occurs in the chloroplasts of
eukaryotic cells and in green pigment molecules
(chlorophyll) of some photosynthetic bacteria
 Photosynthesis uses energy from sunlight to convert
water and carbon dioxide into glucose.
 Oxygen gas is released as a by-product
 The glucose is used to make ATP by cellular respiration in
the mitochondria
 Excess glucose is stored as starch
 Occurs in two major steps:
 Light reactions and Calvin Cycle
Light Reactions (PS I)
 Occur in photosystems (PS I and PS II) that
are embedded in the thylakoid membranes of
chloroplasts.
 Photosystems are groups of chlorophyll
molecules that absorb photons of light
 Chlorophyll electrons in PS I are energized by
sunlight, captured by a primary electron
acceptor, and passed down an electron
transport chain to NADP+ which becomes
NADPH
 NADPH shuttles these energy rich electrons to
the Calvin cycle which occurs in the stroma of
the chloroplast.
Light Reactions (PS II)
 Electrons lost from PS I are replaced by electrons
from PS II.
 Electrons from chlorophyll molecules in PS II are
energized by photons of sunlight, captured by a
primary electron acceptor, and passed down an
electron transport chain to reach PS I.
 As the electrons move down the electron transport
chain the energy lost is used to pump H+ across the
thylakoid membrane, from the stroma into the
thylakoid compartment.
 The H+ then flow through ATP synthase to power
the production of ATP
Products of the Light Reactions
 Electrons lost from PS II are replaced by electrons
that come from the splitting of water at PS II
using the energy absorbed from sunlight.
 Splitting water makes O2 which is released from
the stomata of plant leaves
 ATP and NADPH made during the light reactions
are used in the Calvin Cycle
 The Calvin cycle also requires CO2 which the plant
brings in through the stomata of its leaves
Calvin Cycle
 Occurs in the stroma of the chloroplast
 3 molecules of CO2 enter the Calvin Cycle and
form a chemical intermediate
 This chemical intermediate is phosphorylated
by ATP and reduced by NADPH
 G3P is formed and leaves the Calvin cycle.
 This process is repeated, producing a second
molecule of G3P.
 The two molecules of G3P combine to form 1
molecule of glucose
 ADP and NADP+ are recycled back to the
thylakoids
Chapter 8: Cellular Basis of
Reproduction and Inheritance
 Things to know and be able to do:






Binary Fission
Chromosomes vs. chromatin
Cell cycle stages and control mechanisms
Stages of Mitosis and its purpose in organisms
Cell division and relationship to cancer
Meiosis




Purpose in organisms
Stages
How meiosis causes genetic variation
Potential accidents during meiosis
 Review all notes, labs, review packets and study
guides
 Binary Fission
Cell Division
 Occurs in bacteria
 Results in exact clones of bacteria cells
 The single bacterial chromosome is copied and the cell
divides in half
 Mitosis
 Occurs in Eukaryotes
 Results in 2 daughter cells that are genetically identical
to each other and the parent cell
 Used for growth, repair and development in
multicellular organisms
 Meiosis
 Occurs only in the ovaries and testes of Eukaryotes.
 Makes 4 haploid daughter cells called gametes
Chromatin and Chromosomes
 Refers to the DNA of all organisms when it
is in thin threadlike fibers during interphase
 Prokaryotic DNA forms a single circular
chromosome
 Eukaryotes form numerous chromosomes
made of DNA densely coiled around
proteins
 Always found in the nucleus
 At the beginning of cell division chromosomes
consist of 2 identical copies of DNA called sister
chromatids joined together by a centromere
Stages of the Cell Cycle
 Interphase
 G1: Cell grows, copies organelles, makes
proteins, carries out its function in the
organism
 S: Cell replicates (copies) its DNA
 G2: Cell continues growing and makes proteins
involved in cell division
 Mitotic Phase:
 Mitosis: Nucleus and chromosomes are divided
 Cytokinesis: The rest of the cell including the
cell membrane organelle copies and cytoplasm
divides
Stages of Mitosis (PMAT)
 Prophase
 Chromatin coils and condenses into chromosomes
 Spindle fibers form and attach to kinetochores on each
sister chromatid
 Nuclear membrane breaks up
 Metaphase
 Spindle fibers align chromosomes on the metaphase plate
 Anaphase
 Spindle fibers pull sister chromatids apart and move them
towards the poles of the cell
 Telophase
 Chromatids uncoil
 New nuclear membranes begin to form
 Cytokinesis begins during the end of mitosis
Cytokinesis
 The process that divides cells
 Eukaryotic Animal Cells
 Microfilaments form a ring around the center of the cell
 Microfilaments begin to contract and pinch the center
of the cell together forming a cleavage furrow
 Eukaryotic Plant cells
 Vesicles containing cellulose line up in the center of the
cell
 Vesicles fuse with each other and the edges of the cell
forming a membrane covered cell wall down the middle
of the cell
Control of the Cell Cycle
 Density Dependent Inhibition
 As cell density increases, cell division slows
down and eventually stops
 Anchorage Dependence
 Most cells must be attached to other cells in
order to continue dividing
 Growth factor
 Proteins secreted by neighboring cells that
stimulate cell division in surrounding cells.
 As cell density increases the volume of growth
factor declines and cell division slows
Control of the Cell Cycle
(checkpoints)
 Cells do not proceed through the cell cycle
unless they get “go-ahead” signals at key
check points
 End of G1: Growth factors signal go ahead if
the cell is large enough, has copied organelles
and made enough proteins. Most important.
 End of G2: Growth factors signal go ahead if
cell has correctly replicated DNA during S phase
 Metaphase of Mitosis: Growth factors signal go
ahead if chromosomes are correctly aligned at
metaphase with spindle fibers attached
Cancer is a Disease of the Cell
Cycle
 Cancerous cell divide out of control.
 They do not respond to density dependence
and continue to grow to much higher densities
than normal cells thus creating a tumor
 Some cancer cells, those in malignant tumors,
do not respond to anchorage dependence and
can metastasize. In other words they can
break free from the tumor and begin growing
even when not attached to other tissues, thus
spreading the cancer through the organism
Life Cycles
 Somatic (non-reproductive) cells are diploid.
 They contain pairs of homologous chromosomes.
 Gametes (reproductive cells) are haploid.
 Meiosis divides diploid cells in the testes or ovaries to
produce haploid gametes
 Gametes contain one chromosome from each
homologous pair in an organisms diploid cells
 Fertilization is the union of gametes from two
different individuals as the result of sexual
reproduction.
 Fertilization produces diploid zygotes.
 Zygotes develop into offspring through repeated rounds
of mitosis
Meiosis
 Meiosis is the process that makes haploid
gametes from diploid cells in reproductive
organs.
 Meiosis involves two consecutive rounds of
cell division
 Meiosis results in four haploid daughter
cells with different genetic combinations in
each daughter cell.
 Meiosis has 8 stages divided between
meiosis I and meiosis II
Prophase I:
Meiosis I (PMAT I)
 Pairs of homologous chromosomes, each consisting of
identical sister chromatids, attach to each other and form
tetrads
 Crossing over between non-sister homologous chromosomes
Metaphase I:
 Tetrads line up along the imaginary metaphase plate
Anaphase I
 Tetrads separate, homologous chromosomes in each tetrad
get pulled to opposite poles of the cell. Each chromosome
still consists of 2 connected sister chromatids
Telophase I
 Chromosomes may or may not unwind and new nuclei may or
may not form depending on the species.
 Occurs simultaneously with cytokinesis, which divides the
parent cell into two haploid daughter cells
Meiosis II (PMAT II)
 Prophase II
 Spindle fibers reform in each daughter cell and begin
moving chromosomes towards the center of the cell
 Metaphase II
 Chromosomes line up at the metaphase plate of each
daughter cell
 Anaphase II
 Sister chromatids separate and are pulled to opposite
poles of each cell
 Telophase II
 New nuclei form around the groups of sister chromatids
 Cytokinesis begins dividing each cell into two daughter
cells, for a total of four daughter cells at the end of
meiosis II.
Sources of Genetic Variation
 Independent Orientation: Homologous pairs of
chromosomes can line up in two different
orientations. Each pair orients itself independently
of all other pairs.
 Crossing Over: Non sister homologous
chromosomes can exchange pieces with each
other during synapsis of prophase I. This leads to
new combinations of traits not seen in either
parent
 Random fertilization: The two processes above
produce varied gametes in all parents. Which male
gamete fertilizes a specific female gamete during
sexual reproduction between 2 parents is due to
random chance
Accidents During Meiosis
 Nondisjunction
 Homologous chromosomes fail to separate during
meiosis I
 Results in 4 gametes with abnormal chromosome # (2
with extra, 2 with less)
 Sister chromosomes fail to separate in Meiosis II
 Results in 2 gametes with normal chromosome #, and 2
with abnormal chromosome # (1 with extra, 1 with less)
 Usually results in miscarriage if nondisjunction
occurs between autosomes, but there are
exceptions (down syndrome)
 More survivable if nondisjunction occurs between
sex chromosomes (Turners, Klienfelter)
Accidents During Meiosis
 Alterations of chromosomes: Results from
chromosomes breaking during meiosis
 Deletions: missing a piece altogether, usually the
most serious
 Duplication: When a piece of one chromosome
breaks off and is added to its homolog, Resulting
in 2 copies of the genetic information
 Inversion: When a piece breaks off of one
chromosome and then is reattached upside down
to the same chromosome
 Translocation: When a piece breaks off and
attaches to another non-homologous chromosome