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392 Cards in this Set

  • Front
  • Back
What is the term for "similarity by descent from common ancestor"?
Genes that evolved from an ancestral gene are called what and found in whom?
Homologous Genes
Humans and Animals
What are the two ways to generate variety in heredity?
1) Mutation
2) Swapping of DNA
What does the mutation, exon "shuffling" imply?
Recombining different coding regions of different genes to make new genes/proteins.
What are the two big mutation options that can rearrange chromosomes?
1) Exon "Shuffling"
2) DNA rearrangement to provide genes with new Transcription Factors
When DNA rearrangements occur (type of mutation) to provide different transcription factors, what is occurring?
One coding region may be dependent on an unrelated promoter-operator system.
The Green Fluorescent Protein (GFP) coding regions from jellyfish were fused to enhancer-promoter DNA. What happened? This is an example of what?
Regional expression of Green Fluorescent Protein (GFP).
DNA rearrangements to give genes new transcription factors.
Variation is needed for?
How do Eukaryotes swap DNA?
Mostly via sex.
How do Prokaryotes swap DNA?
No real sex, but can exchange parts of DNA via:
1) Transformation
2) Conjugation
3) Transduction
What two steps take place during prokaryotic cell division?
Fission into two "daughter" cells.
Replicate circular chromosome DNA.
In prokaryotic/bacterial exchange of DNA:
"Take up DNA from outside"
In prokaryotic/bacterial exchange of DNA:
"Direct transfer of DNA from another bacterium"
In prokaryotic/bacterial exchange of DNA:
"Transfer DNA via bacterial virus (phage)"
Name an example of transformation (bacterial exchange of DNA).
Griffith's experiment with smooth and rough bacteria for pneumonia.
Define transformation as it relates to bacterial exchange of DNA.
Taking up DNA from outside of cell and incorporating it into the chromosome.
Which of the Prokaryotic versions of swapping DNA is the most similar to that of Eukaryotic "sex"?
What connects the bacterial cells during conjugation?
A long extension of membrane called a Pili.
What are plasmids?
Small, circular DNA that is not part of chromosomes that can be passed via conjugation over a mating bridge.
Recombination of DNA can occur when chromosomes are passed by what process?
Why are plasmids (especially their being passed during conjugation) important?
They can carry valuable information. For example, R plasmids carry mutant genes that make bacteria resistant to antibiotic drugs.
What does the act of "transduction" rely upon to transfer DNA?
What is an infectious agent smaller than bacterium (parasite on cell)?
Where do viruses reproduce?
In the host cell.
What two things do viruses contain?
Proteins and Nucleic Acids
What is the nucleic acid (DNA) from a virus wrapped up in?
Capsids (proteins sometimes with membrane lipid envelope)
What are the two cycles that viruses undergo to make more viruses?
1) Lytic Cycle
2) Lysogenic Cycle
What are the five steps to the Lytic Cycle?
1) Attachment
2) Entry of phage DNA and degradation of host DNA
3) Synthesis of viral genomes and proteins
4) Assembly
5) Release
During the Lytic Cycle, during transcription and translation, what kind of proteins are made?
Capsid Proteins
What is the end product of the new viral DNA inclosed in a capsid protein "membrane"?
Phage which is released into environment to infect more cells.
During the Lysogenic Cycle, what is different about the viral DNA when it enters the host cell?
Lysogenic - Phage DNA integrates into the bacterial chromosome.
Lytic - Phage DNA enters and replaces the old chromosomal DNA.
Viruses' genetic material for Eukaryotic hosts can be made of what?
double-stranded or single-stranded
What is the enzyme that converts retrovirus RNA to DNA?
Reverse Transcriptase
What is a significant real-world virus that is converted via Reverse Transcriptase?
HIV virus --> AIDS
Viral diseases can begin what two ways?
1) Virus takes over and disrupts tissues by producing more virus
2) Virus imports and abnormally expresses genes from humans and others
What are three difficulties with Primordial Soup?
1) Synthesis problems - what does it take to get the molecules?
2) Clutter and diffusion problems - membranes
3) Chirality - in cells most sugars are right-handed, A.A. and left-handed
Freeze-Thaw cycles were featured in Miller's freezer "experiment". What did he create/discover?
Organic molecules that convert from one chiral form to the other.
What is the only possible self-replicating polymer?
RNA (can do both; template for RNA and for enzymes)
What are the steps of the "Two-Step Self-Replication" of RNA?
1) begin w/ RNA monomers
2) formation of short RNA polymers
3) assembly of a complement RNA chain
4) complementary chain serves as the template for making a copy of the original "gene"
Natural Selection will operate if...?
If a small number of self-replicating molecules are generated.
How did ancient cells begin?
Self-replicating RNA acted as a template for forming proteins (?)
Proteins then aid in replication of RNA.
What are the four steps of the "RNA World" hypothesis?
1) RNA-->RNA (self-replication)
2) RNA-->Protein (more enzymes)
3) RNA-->DNA (better storage of nucleotide sequence)
4) DNA-->RNA
Why is the "RNA World" hypothesis hard to support?
No modern RNA self-replication.
What is the modern "DNA World" in contrast with the "RNA World" hypothesis?
1) RNA does not self-replicate
2) DNA-->DNA
3) DNA-->RNA
4) RNA-->protein
What were primitive membranes possibly made of?
Fatty acids.
How did the primitive fatty acid membranes compare to phospholipid membranes?
Much more permeable; polar organic monomers will get inside fatty acid liposome (food (glucose), nucleotides, etc.)
Once polar organic monomers got inside of the primitive fatty acid membranes, what happened to them?
They polymerized and were trapped.
What caused cell division with primitive membranes?
Osmosis swelling the liposome.
What are the three categories of membrane-bond "organelles" in Eukaryotes?
1) Nucleus
2) Endo-Membrane System
3) Semi-Autonomous Organelles
What is the category of organelles that consists of tiny little organism like things within the cell?
Semi-autonomous organelles.
What three things make up the nucleus?
1) Chromatin
2) Nucleolus
3) Nuclear Envelopes
What are chromatin?
Strands of chromosomes (looks like mush).
What is the nucleolus the site of?
rRNA synthesis and assembly of large/small ribosomal subunits.
What is the nuclear envelope made up of?
Two lipid bilayers (inner and outer).
(equates to four rows of lipids)
Nuclear "pores" perforate what?
Inner and outer nuclear envelopes.
Nuclear "pores" in the inner and outer nuclear envelopes provide what kind of transport?
Active transport complex of about 30 different kinds of proteins. Selective to certain criteria. Recognizes with lock and key mechanism.
What is mRNA sorting?
Binds adaptor and export proteins that interact with pores. Different adaptors for ribosome subunits, tRNA.
What is the Signal Sequence during protein sorting and what does it allow for?
Amino acid sequence that allows binding to nuclear import protein.
What two organelles make up the endomembrane system?
Endoplasmic Reticulum
Golgi Apparatus
The endomembrane system trafficks what?
Transmembrane Proteins which are exported from the cell (secreted)
Which organelle does this describe:
Network of membrane-enclosed tubes, discs that is continuous with the other nuclear envelope.
Endoplasmic Reticulum (ER)
What differentiates the Rough ER from the Smooth ER?
Ribosomes (Rough)
What happens at the Rough ER?
Protein Synthesis
What is synthesized at the Smooth ER?
Phospholipids and Steroids
Besides phospholipid and steroid synthesis, what does the Smooth ER do?
Processing, storage (of Ca2+, others, etc.)
What did the Pulse-Chase experiment with radioactive Amino Acids discover?
Route of proteins through cells.
Early: Rough ER
Mid: Golgi
Late: Outside cell
In the Pulse-Chase experiment, the "pulse" contained what kind of A.A?
Radioactive Amino Acids so their route could be seen.
In the Pulse-Chase experiment, the "chase" contained what kind of A.A?
Non-radioactive Amino Acids so the "pulse" protein path could be seen.
Transmembrane and secreted proteins are made where?
Outside of Rough ER
What does the ER signal sequence do?
Allows insertion of proteins into the interior of the rough ER through ER membrane.
Which organelle does this describe:
Stack of flattened membrane-bound discs.
Golgi Apparatus
The Golgi has two sides, which side do proteins enter? Which side do they leave?
Enter --> Cis
Leave --> Trans
Which organelle processes proteins?
Golgi Apparatus
What are the three ways proteins can be processed?
1) Cleaved to make smaller polypeptides
2) Linked to other proteins
3) Linked to other molecules, especially carbohydrates
What does glycosylation do?
Links carbohydrates (saccharides) to other molecules (proteins).
Which type of cells are central vacuoles found in?
Plant and Fungal cells.
The central vacuole has a role in what three things?
1) Digestion
2) Processing
3) Storage
What do transport vesicles do?
Take proteins from ER to Golgi (cis side).
What do secretory vesicles do?
Take proteins/cargo from Golgi (trans side) to outside of cell.
What is a common ending for vesicles (many exceptions)?
(endosomes, exosomes, lysosomes...)
Which kind of vesicles contain digestive enzymes?
What is the correct order of Protein Secretion?
ER --> Transport Vesicle --> Golgi Apparatus --> Secretory Vesicle
Where do proteins originate?
Ribosomes on ER (not at nucleus)
What happens to the lipids that are secreted from a secretory vesicle?
Primarily end up in the cell membrane.
How do vesicles move?
Motor proteins move the vesicles along the cytoskeleton.
What is the cytoskeleton made up of?
Intracellular rods and fibers that support the cell.
What can the cytoskeleton be broken down into (3 things) in Eukaryotes?
1) Microtubules
2) Microfilaments
3) Intermediate Filaments
Microtubules in the cytoskeleton are characterized how?
Thickest diameter. Helical polymer made of individual dimers of α - and β - Tubulin proteins.
Microfilaments in the cytoskeleton are characterized how?
Finest diameter.
What is the structure of microtubules?
Helical polymer made of dimers. Dimers are made of α and β tubulin proteins.
What is the function of microtubules?
Provide structure and help move things in/through cell.
How do microtubules move things?
1) Push or pull things by rapid lengthening or shortening
2) Using attached motor proteins (which "walk" along microtubule)
3) Sliding past each other using motor proteins
What organizes microtubules into a useful structure?
Centrioles in Centrosome
What is the relationship between microtubules, centrioles and centrosomes?
9 microtubule triplets make up a centriole. A centriole pair makes up a centrosome.
What are intermediate filaments used for?
Structural meshwork under the membrane.
What are "fine, bendable projections from cell, enclosed by a cell membrane"?
Cilia / Flagella
What is the difference between cilia and flagella?
Cilia = short, many
Flagella = long, few
What is the function of cilia and flagella?
Push water in coordination to move the cell.
Cilia and flagella are made up of what?
Sliding microtubules (9 pairs in ring + 2 in center = "9+2").
Pairs are connected by the motor protein Dynein.
What is the structure of a microfilament?
Double helix of Actin proteins.
How do microfilaments move?
1) Shortened or lengthened by removal or addition of actin proteins
2) Slide past each other using the motor protein Myosin
Which motor protein works in conjunction with microtubules?
Which motor protein works in conjunction with microfilaments?
Microfilaments are commonly named with which ending?
What are the three main functions of microfilaments?
1) shortens muscles - contraction (muscle cell made of actin and myosin)
2) other changes in cell shape to move it
3) cytoplasmic "streaming" in plants (circulates cytoplasm)
What are the two semi-autonomous organelles?
Where does most of the energy in eukaryotes come from?
Semi-Autonomous Organelles
Which organelle produces chemical energy from sugars and other compounds?
Which process does the mitochondria do?
Cellular Respiration
Which organelle is found in plants and some protists (single-celled eukaryotes) that produces energy from sunlight?
Chloroplasts produce energy during which process?
Why are the mitochondria and chloroplasts considered "semiautonomous"?
They contain some of their own DNA, mRNA, and ribosomes which allows them to reproduce; resemble free-living bacteria.
When organisms live together in direct and intimate contact they are doing ____.
What is the concept behind Endosymbiont Theory?
A prokaryotic cell swallowed by endocytosis into a eukaryotic cells stays and provides the energy the eukaryotic cell needs.
Where do endosymbionts get their nutrients?
Host cell
Endosymbionts provide what for their host cell?
ATP / energy
What is this reaction?
Glucose + 6 O2 --> 6 CO2 + 6 H2O + energy (ATP)
Cellular Respiration
What are the three steps to Cellular Respiration
1) Glycolysis
2) Krebs Cycle
3) Oxidative Phosphorylation
Where do each of the steps of respiration take place?
Glycolysis - Cytoplasm
Krebs Cycle & Oxidative Phosphorylation - Mitochondria
In Glycolysis, glucose is "lysed" into?
2 x 3-C Pyruvates
In redox reactions, atoms that gain electrons are?
Reduced (reduces charge)
In redox reactions, atoms that lose electrons are?
Oxidized (like losing electrons to O)
NADH and FADH2 are examples of what?
Electron carriers
What do electron carriers do?
Carry electrons from glucose to electron transport chain.
What are the inputs and outputs for Glycolysis?
1 molecule glucose
4 ADP + Pi
2 NAD+

2 pyruvate
2 ADP + Pi
What is the net energy output for Glycolysis?
2 ATP and 2 NADH
Electrons are captured where during glycolysis?
In the Intermediate stage between Glycolysis and the Krebs Cycle, what happens to the Pyruvate molecules?
Enters the mitochondrian matrix where it loses 1C as CO2 and binds to Coenzyme A to make Acetyl-CoA
What are the inputs and outputs for the Intermediate stage of Cellular Respiration?
2 Coenzyme A
2 Pyruvate
2 NAD+

2 Acetyl-CoA
2 CO2
What is the net energy output for the Intermediate stage (2 molecules of pyruvate)?
Where does the Acetyl CoA enter into the Krebs Cycle?
Mitochondrian Matrix
What does the acetyl-CoA add to during the Krebs cycle? What does it form?
Acetyl CoA binds to 4-C oxaloacetate to form citric acid.
The Krebs Cycle reduces the citric acid it formed initially to what?
2-C molecules (CO2) and 4-C oxaloacetate
What are the inputs and outputs of the Krebs Cycle (assuming 2 molecules of Acetyl-CoA)
2 Acetyl CoA molecules
6 NAD+
2 Oxaloacetate
2 ADP + Pi

4 CO2
2 Oxaloacetate
What is the net energy output for the Krebs Cycle (2 molecules of Acetyl-CoA)?
Glucose is reduced to 6 CO2 in what stages?
2 Krebs Cycles
How many molecules and what types of molecules of electron carriers are created per glucose molecule?
When are the electrons stored in NADH and FADH2 converted to energy?
During Oxidative Phosphorylation
What is "Substrate-Level Phosphorylation"?
Glycolysis and Krebs Cycle make ATP by taking phosphate from high energy "substrate" molecule and binding to ATP.
What are the two stages of Oxidative Phosphorylation?
1) Electron Transport Chain
2) ATP Synthesis
How does the Electron Transport Chain work?
Electrons stored in NADH and FADH2 pump H+ into the space between mitochondrial membranes
How does ATP synthase make ATP?
Uses the diffusion gradient of H+ across membrane to bind ADP and Pi to make ATP.
Why is the inner membrane of the mitochondria folded?
To increase surface area and allow for more proteins to pump more H+ and ultimately make more ATP.
What is at the end of the electron transport chain?
Oxygen; which makes H2O (also pumps H+ across the inner membrane.
What are the inputs and outputs for Oxidative Phosphorylation?
6 O2
34 ADP + Pi

34 ATP
6 H2O
10 NAD+
What is the net energy output for Oxidative Phosphorylation?
34 ATP
What are the molecules that are donors and acceptors of electrons in the Electron Transport Chain?
NADH and FADH2 (donors --> oxidized)
O2 (acceptor --> reduced)
Which metal atoms often carry electrons?
Iron or Copper ions which are surrounded by protein
What is an iron-containing ring?
Heme, similar to heme that carries O2 in blood.
In Oxidative Phosphorylation, which molecule acts like a turbine?
Mitochondrial ATP Synthase
How does ATP synthase act like a turbine?
H+ diffusion through channel spins channel proteins which catalyzes the synthesis of ATP.
What is the sum of ATP created by each level of Cellular Respiration?
Glycolysis = 2 ATP
Krebs Cycle = 2 ATP
Ox. Phos. = 28-34 ATP
Total = 32-38 ATP
How efficient is cellular respiration in getting energy from glucose molecules?
40% efficient, compared to 25-30% efficient in a gas engine
Where does the "lost" energy, during cellular respiration, go?
Released as heat to the body.
What is another reason that mitochondria may have evolved from prokaryotes in regards to H+ diffusion?
Some prokaryotes have electron transport chains w/ ATP driven pumps to get H+ from outside of the cell.
Why do some prokaryotes have pumps that bring H+ into the cell?
Reduces acidity of cytoplasm and drives cotransport; allows them to synthesize ATP from ADP and P.
What would happen if there was no oxygen present for Cellular Respiration?
Electron Transport Chain would quickly stop pumping H+ ions (NADH and FADH2 would pile up and occupy space).
Cell would start to run out of NAD+ which would shut glycolysis and Krebs cycle down.
Which kind of process uses oxygen?
Which kind of process does not use oxygen?
What is the solution to not having Oxygen (and not being able to change NADH back to NAD+ which is required for glycolysis and Krebs)?
Add steps to glycolysis to regain NAD+ from NADH => Fermentation!
What is the purpose of fermentation?
To get NAD+ for glycolysis if there is no O2 to get NAD+ in the Oxidative Phosphorylation stage.
What are the two types of fermentation?
1) Lactic Acid Fermentation
2) Ethanol Fermentation
How much energy does fermentation yield?
2 ATP per glucose molecule
Do the products of fermentation enter the Krebs Cycle?
What does allosteric regulation mean?
The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
What controls the rate of respiration using negative feedback?
Enzyme activity with allosteric regulation.
Example: ATP or Citric Acid inhibits glycolysis
What are other sources of energy besides sugars?
Other organic molecules
(proteins --> amino acids --> pyruvate, acetyl CoA
or glycerol --> glycolysis
or fatty acids --> acetyl CoA)
Do the products of fermentation enter the Krebs Cycle?
What is the equation for Photosynthesis?
6 CO2 + 6 H2O + energy --> 6 C6H12O6 +6 O2
What does allosteric regulation mean?
The binding of a regulatory molecule to a protein at one site that affects the function of the protein at a different site.
Where is photosynthesis performed?
Chloroplasts (one of the semi-autonomous organelles in eukaryotes)
What controls the rate of respiration using negative feedback?
Enzyme activity with allosteric regulation.
Example: ATP or Citric Acid inhibits glycolysis
Where do plants get most of their non-water mass from?
Atmosphere (CO2)
What are other sources of energy besides sugars?
Other organic molecules
(proteins --> amino acids --> pyruvate, acetyl CoA
or glycerol --> glycolysis
or fatty acids --> acetyl CoA)
Why do chloroplasts have two membranes?
Original membrane + membrane from endocytosis into eukaryotic cell.
What is the equation for Photosynthesis?
6 CO2 + 6 H2O + energy --> 6 C6H12O6 +6 O2
The stroma is made up of what three parts?
Stroma, Thylakoids, and Grana
Where is photosynthesis performed?
Chloroplasts (one of the semi-autonomous organelles in eukaryotes)
In a chloroplast, what is the stroma?
The space inside of the inner membrane.
Where do plants get most of their non-water mass from?
Atmosphere (CO2)
Why do chloroplasts have two membranes?
Original membrane + membrane from endocytosis into eukaryotic cell.
The stroma is made up of what three parts?
Stroma, Thylakoids, and Grana
In a chloroplast, what is the stroma?
The space inside of the inner membrane.
In the chloroplast, what are thylakoids?
Membrane-bound discs in the stroma.
In the chloroplast, what are grana?
Stacks of thylakoid; inside of stroma.
Where do the light reactions take place?
In thylakoid membranes of chloroplasts.
Obviously light is required for "light" reactions; what is produced?
ATP, electrons in NADPH, and O2
Where do the dark reactions take place?
In the stroma of chloroplasts.
If the dark reactions don't require light to function, what powers this process?
ATP, electrons in NADPH, and CO2
What does the dark reaction create?
Sugars (NADP+ and ADP + Pi)
What is another name for the dark reaction?
Calvin Cycle
What are the three stages for the Calvin Cycle (Dark Reaction)?
1) Carbon "fixation"
2) Reduction
3) Regeneration of RuBP
How many cycles of the Calvin Cycle must be completed in order to get 1 glucose molecule?
3 times through
In the Carbon Fixation stage of the Calvin Cycle, what occurs?
Rubisco enzyme adds CO2 to 5-C RuBP
3 CO2 + 3 RuBP --> 3 6-C --> 6 3-C
In the Reduction stage of the Calvin Cycle, what occurs?
Produces 6 G3P molecules, 1 of which is removed from cycle to make sugars
In the Regeneration of RuBP stage of the Calvin Cycle, what occurs?
Remaining 5 G3P's + ATP regenerate 3 5-C RuBP (starting material)
How much energy is required to go through the Calvin Cycle three times?
9 ATPs, electrons in 6 NADPHs
What absorbs light energy?
What are the main pigments in chromosomes?
Chlorophyll a and b
What does the light energy do to pigments?
Light excites the electrons in the (magnesium-containing) ring to higher, unstable energy.
What are accessory pigments called?
What are the purpose of cartenoids?
To absorb different wavelengths of light that the pigments (chlorophylls) can't absorb (could damage/bleach the chlorophyll).
When can you see cartenoids?
In the fall when the chloroplasts (green) die, the yellow-orange color is exposed.
What do pigments do in relation to photosystems?
Utilize light to excite and donate electrons to electron acceptors (donated e- are replaced by taking two from H2O to make oxygen:
2e- + 2H + 1/2 O2)
Which mechanism does the following:
"gives high-energy e- to H+-pumping electron transport chain"?
Photosystem II
What are the two parts that make of Photosystem II?
1) Pumps H+ into thylakoid
2) H+ gradient drives ATP Synthase
Which mechanism does the following:
"gets and excites e- from H+-pumping electron transport chain"?
Photosystem I
Where do the excited electrons go during Photosystem I?
1) Go to NADP+ to make NADPH (non-cyclic/Z scheme)
2) Go back to H+ pumping electron transport chain to make ATP (cyclic scheme)
What does the Non-Cyclic or Z scheme produce?
Equal amounts of ATP (via H+ pumps) and NADPH (after Photosystem I).
What does the Cyclic scheme do?
Makes extra ATP (no NADPH) by electrons going back to the H+ pumps after arriving at Photosystem I).
Why does the Cyclic scheme exist?
The Calvin Cycle requires 9 ATPs and 6 NADPH; the Non-Cyclic scheme makes equal quantities, must make extra ATP somehow.
Plants get almost all of their energy from where?
Plants get almost all of their carbon from where?
Plants get almost all of their electrons from where?
Cells who get their carbon from organic sources are called?
Cells who get their carbon from inorganic sources are called?
Cells who get their energy from molecules are called?
Cells who get their energy from sunlight are called?
What are the electron donors and acceptors in plants?
Donor = H2O (in chloroplast)
"Final" Acceptor = Oxygen (in mitochondria) (+ reduced organic molecules)
What are the electron donors and acceptors in animals and fungi?
Donor = Reduced organic molecules (in glycolysis & Krebs)
"Final" Acceptor = Oxygen (in mitochondria) (+ reduced organic molecules)
What are protists?
Single-celled eukaryotes; first discovered 2 billion years ago.
What are the two types of eukaryotes?
Protists and Multi-Cellular
What is a colony? What does it sometimes get confused with?
Collection of "individuals" (protists & prokaryotes form colonies). Must be differentiated from "true multi-cellularity".
Which types of things experience true multicellular life?
Fungi, Plants, Animals
Plant and fungi cells have what feature that animal cells don't have?
Thick, stiff cell walls outside of the cell membrane.
Fungi have "cells" in long tubes called?
What makes up the cell wall of a fungi?
Chitin polysaccharide
What separates the wall and membrane of a fungi cell?
What allows the fungi cell to pass objects from to other cells? What is it big enough to pass?
Pores in walls connect membranes big enough for nuclei to move through.
What are fused cells, many shared nuclei, called?
In plants, cell walls are made up of what?
Cellulose polysaccharide
What are the names of pores in the cell walls of plants?
What do plasmodesmata do for plant cells?
Pass proteins and RNA; connects smooth ER of two cells; therefore whatever you make in one cells' ER can be passed to the other cells.
Since animal cells do not have a cell wall, what do they have instead?
Jelly-like Extracellular Matrix
What is the extracellular matrix made up of & what are the name of the structures?
Proteins and polysaccharides
Collagen and Chondroitin Sulfate
In the ECM, what are the long protein fibers?
In the ECM, what are the long polysaccharides?
Chondroitin Sulfate
What are the small pores between some animal cells? (Not syncytial)
Gap Junctions
Gap junctions allow passage of what kinds of molecules?
Small: monomers, ions, NOT macromolecules.
How do animal cells stick together?
Cell Adhesion Molecules (CAMs)
Cell Adhesion Molecules (CAMs) do what?
Transmembrane proteins with specific lock and key binding to adjacent cells.
List the three types of binding that adjacent cells can do.
1) Homophilic - binds to identical molecule on other cell
2) Heterophilic - binds to a different molecule on other cell
3) Indirect binding by a linker molecule
What are the two animal cell arrangements?
1) Connective tissue (mesenchyme) = cells relatively loose
2) Epithelium = tightly attached cells organized into flat sheet
What are the two sides of the epithelia cell called? How are they differentiated?
Apical & Basal
Polarized; basal side attached to the basal lamina
What is the basal lamina? What type of cell arrangement is it associated with?
Extracellular Matrix that underlies the basal side of Epithelium cells
What is an example of the type of specialized CAM that forms a junction between epithelial cells?
Homophilic Cadherin
What is an example of the type of specialized CAM that forms a junction from an epithelial cell to the extracellular matrix?
Cells can signal via cytoplasmic connections; what are these in fungi/plants/animals?
Fungi (syncytial cells) can pass anything.
Plants: Plasmodesmata
Animals: Gap Junctions
What is a signaling molecule, that communicates between cells without a cytoplasmic connection, called?
Short range signals without cytoplasmic connections are ___.
Membrane bound.
Short or long range signals without cytoplasmic connections are ___.
What does the signaling molecule do?
Binds and activates a specific receptor by changing its shape.
What is an example of a signal that can be secreted through the membrane?
Lipids (steroids: estrogen, testosterone, etc)
What are the three steps of "steroid transduction"; or in other words, its pathway to effect?
1) Steroids bind to receptor protein in cytoplasm and nucleus
2) Receptor-steroid complex is a transcription factor that binds to DNA
3) Turns on transcription of genes with matching enhancer DNA
What kinds of signals can diffuse through the lipid bilayer?
Lipids and gasses.
What kinds of things can't diffuse through the lipid bilayer?
Proteins, amino acids, etc.
What are the three things that can vary in signal transduction?
1) Range inside cell - entire cell or local effect
2) Amplification - only if activated molecule is an enzyme
3) Feedback - positive or negative
What is an example of a case when the signal transduction does not amplify?
Activated G protein binds and activates a single target protein.
What is an example of a case when the signal transduction does amplify?
Protein Kinases = enzymes that add phosphates to specific proteins, activating or inactivating them (can phosphylate infinite proteins - cascades)
Which type of feedback amplifies or lengthens the time of the signal?
Positive feedback
Which type of feedback decreases or shortens the time of the signal?
Negative feedback
What are small, non-protein molecules used for signal transduction?
Second Messengers
What are three big examples of second messengers?
1) Lipids - from membrane lipids
2) Cyclic AMP (cAMP)
3) Ca2+ (from outside cell or storage in ER)
What does Cyclic AMP (cAMP) do?
Stimulates protein kinase A.
Can a second messenger also be a signal between cells?
Yes (through fungi, plants and animals: gap junctions)
Do all multicellular eukaryotes have sexual reproduction?
No! (asexual reproduction = from single parent; ex: hydra, redwoods)
Sexual reproduction requires what two things?
Two parents: egg + sperm of germline.
The egg germ line is characterized by what characteristics?
Immobile, larger, contains yolk.
What is the purpose of yolk in eggs?
Provides proteins as nutrients.
The sperm germ line is characterized by what characteristics?
Mobile, smaller, usually swims using a flagellum
What occurs during fertilization?
Sperm membrane fuses with the egg membrane (nucleus in sperm joins with the nucleus in the egg to form one, big nucleus).
What is the first step during sexual reproduction (after the egg and sperm join)?
The fertilized egg divides to form an embryo.
What are the first divisions of an embryo called?
Cleavage (cells do not move, can occur without growth)
What does the cleavage of the embryo produce?
Blastula (bunch of cells).
What are the three Germ Layers of the Gastrula?
1) Ectoderm
2) Mesoderm
3) Endoderm
Which layer of the gastrula is described as the outermost; makes skin and nervous system?
Which layer of the gastrula is described as in the middle; makes the muscles and internal organs?
Which layer of the gastrula is described as the innermost; makes the digestive system?
After the gastrula is formed, what is the next step?
What is organogenesis?
When each germ layer subdivides into specific organs (skin, brain, heart, liver, muscles, intestines, etc)
What is the formation of the Central Nervous System called?
The ectoderm (outermost cells) pinches off a long tube on the dorsal side called what? What does this tube become?
Neural tube - forms the brain and spinal cord.
Spina bifida occurs when what fails?
Occurs when the neural tube fails to close.
What is "differentiation"?
At all steps during sexual reproduction, cells are assuming different roles.
Do differentiated cells have different DNA?
No, all cells contain the same DNA.
What does cloning have to do with differentiated cells?
Cloning is making an embryo that contains the DNA from a differentiated adult cell.
What was the protocol in cloning, Dolly for example?
1) Take differentiated (mammary) cell from donor
2) Take egg cell from ovary (remove nucleus)
3) Fuse cells (input nucleus from mammary cell into egg cell)
4) Grown in culture
5) Implanted in uterus of 3rd sheep
6) Embryonic development
(Dolly = chromosomally identical to mammary cell donor)
What makes differentiated cells different?
Same genes (DNA) but different gene expression (mRNA, protein).
How do differentiated cells become different? (2 reasons)
1) Different signals from different parts of embryo
2) Different "determinants" inherited during cell division
How can cells change differentiation?
Signals from one set of cells can change the differentiation of adjacent cells.
What is the name for a molecule inherited by only one daughter cell (from parent cell) that makes the cell different from the other daughter cell?
Cytoplasmic Determinant
What is this an example of:
When frog embryo cells divide, one cell may inherit the grey crescent which makes that cell normal, whereas the cell without the grey crescent piece will be a belly piece.
Cytoplasmic Determinant
What are cytoplasmic determinants made of?
Not always known; but some are proteins or mRNAs that instruct cells to make specific proteins.
True or False?
Most embryos use either cell-cell signaling or cytoplasmic determinants.
False. Most embryos use both.
What does the term potency mean about a cell?
The cell has the capability to differentiate depending on external signals; could become more than one type of cell.
When cells are early in development, they can become several types of cells. This is referred to as being?
When a cell loses it's pluripotency it is called?
Cells that do not lose their pluripotency are called what?
Stem Cells
What cells divide and increase the cell number, without necessarily growing...
What occurs during the S or Synthesis Phase of the Cell Cycle?
DNA Replication
What occurs during the M or Mitotic Phase of the Cell Cycle?
Division of the cell.
What is the period in between the M and S phases?
Gap 1 (G1)
What is the period between the S and M phases?
Gap 2 (G2)
What is the abbreviated version of the Cell Cycle?
Interphase: G1 --> S (synthesis) phase --> G2 -->
M (mitotic) Phase: Mitosis --> Cytokinesis
When do the three checkpoints in the Cell Cycle occur?
1) G1 Checkpoint - towards end of G1 Phase
2) G2 Checkpoint - in between G2 phase and Mitotic phase
3) M Checkpoint - during Mitosis
What is required at the G1 checkpoint?
That the cell is large enough, has the nutrients it needs, proper signals.
What is required at the G2 checkpoint?
DNA needs to be duplicated; checks for accuracy. (Cells can stay here a while if necessary).
What is required at the M checkpoint?
Chromosomes are attached to cytoskeleton for movement; if not, DNA won't be moved to daughter cell.
What are the places of vulnerability during the cell cycle?
Checkpoints; failure here could lead to cells dividing when not ready and creating cancers.
How do prokaryotes divide their cells?
DNA in circular chromosomes are duplicated. Cell divided by fission into two "daughter" cells.
Eukaryotic Chromosomes are made up of what?
Linear DNA in a complex with proteins (humans have 46 per cell)
What is the difference between mitosis and meiosis?
Mitosis creates two cells with the same DNA as the parent.
Meiosis creates four daughter cells with half the DNA of the parent (need for fertilization).
Eukaryotic chromosomes | or X ^
When DNA replicates, each | | making up the X is called?
Sister Chromatids
What are sister chromatids joined by to form a chromosome (X)?
Mitosis separates a "single" chromosome of two chromatids into?
Two single chromatids, or in other words two chromosomes.
A chromatid is made of what?
A single double helix.
A chromosome has how many double helices?
It depends. Before replication = 1 double helix
After replication = 2 double helices
What are the ends of the chromatids / chromosomes called?
What are microtubules organized by?
Centrosome: made of two centrioles.
What is the function of the mitotic spindle?
Arranges and moves chromosomes during mitosis.
What are mitotic spindles made of?
Microtubules radiating from two centrosomes at poles of the cell.
What makes of a centrosome?
A pair of centromeres.
What is the protein that surrounds the centromere and controls movement of the mitotic spindle?
What two ways can a kinetochore move the microtubules of the mitotic spindle?
1) Shortening: microtubules disassembled at kinetochores and sometimes at poles
2) Sliding using motor proteins (with use of ATP)
What happens to the nuclear envelope during mitosis?
Remains in a few protists and yeasts, but in most eukaryotes it is broken apart.
What are the phases of Mitosis?
-- G2 of Interphase
1) Prophase
-- Prometaphase
2) Metaphase
3) Anaphase
4) Telophase
What occurs during the Prophase stage of Mitosis?
Chromosomes condense, spindles form, centrosomes move towards poles, nuclear envelope breaks down.
What occurs during the Metaphase stage of Mitosis?
Chromosomes line up along the metaphase plate.
What occurs during the Anaphase stage of mitosis?
Chromatids separate, move towards poles of cell.
What occurs during the Telophase stage of Mitosis?
Reform nuclei; begin cleavage of cell.
When does the cell subdivide into two cells (mitosis)
What is the difference in cytokinesis for animal and plant cells?
Animals - form "Cleavage Furrow"
Plants - form "Cell Plate"
In order for the cleavage furrow to divide an animal cell, what is necessary?
Contractile ring of microfilaments (actin / motor proteins) and myosin.
In order for a plant cell to divide after telophase, what is built?
Cell plate.
Why do plants have to form a cell plate instead of dividing like an animal cell with a cleavage furrow?
The cell wall and turgor pressure present the cell from cleaving; instead build a new membrane within the cell (cell plate).
Mitosis only occurs in which kind of animal cells?
Can haploid cells undergo mitosis?
Not animal cells; other organisms can to produce more haploid cells (haploid multicellular organisms).
What are haploid multicellular organisms that can undergo mitosis?
What are diploid multicellular organisms (en route to becoming haploid multicellular organisms that undergo mitosis) called?
Going from Diploid (2n) to Haploid (1n) cells occurs during which cell cycle?
What type of cell are sperm and eggs?
What occurs during fertilization?
Two haploid gametes are combined to make a diploid zygote.
What are pairs of chromosomes in diploid cells called (not copies; separately inherited from each parent)
Homologues have same genes but can have different ____?
The first part of meiosis separates what?
Homologous chromosomes
Women have 46 total chromosomes. How many homologous pairs?
Men have 46 total chromosomes. How many homologous pairs do the sperm have?
None - no pairs.
Haploids have how many homologues (not to be confused with pairs)?
Diploids have how many homologues?
Two - one from sperm, one from egg
What is the general process of Meiosis?
1) DNA replicates
2) Meiosis I
3) Meiosis II
What happens during the first round of meiosis?
Homologous chromosomes line up next to each other and separate; sister chromatids stay together.
What happens during the second round of meiosis?
Second division to halve amount of DNA; sister chromatids separate.
New haploid cells mature to become eggs or sperm.
What is the term for gametes only getting one of the two possible alleles?
Why did Mendel utilize pea plants?
Could control how they mated (artificial cross-pollination)
Heritable differences that were easy to follow (flower color, seed color, seed shape)
What is the phenotype?
Physical traits the individual has.
What is the genotype?
What genetic information the individual can pass on.
What does it mean to be homozygous?
Both alleles of a gene are identical.
What does it mean to be heterozygous?
One of the two alleles of the gene is different.
What does it mean to be a dominant allele?
Controls the phenotype even if only one homologue has that allele.
What does it mean to be recessive?
Controls phenotype only if both homologues have that allele.
What is the "Law of Segregation"?
Two alleles in parent "segregate" from each other during formation of gametes (sperm, eggs).
What follows two genes at the same time?
Dihybrid Cross
During a dihybrid cross, what is assumed?
The two genes are on different (non-homologous) chromosomes.
What is the expected ratio in a dihybrid cross?
What is the formula for determining the possible combinations of homologues?
2^N combinations
N = homologue pairs being considered
What kind of gametes do you mate to determine which trait is dominant?
Two homozygotes.
What are the four complications with Mendelian inheritance?
1) What if gene is on a sex chromosome (sex-linked)?
2) What if an allele is not really dominant or recessive?
3) What if two genes are on the same chromosome?
4) What if inheritance is non-Mendelian?
What are non-sex chromosomes called?
What does it mean to be "sex-linked"?
Genes are found on the sex chromosome.
(Example: no versions of X-linked genes on Y chromosome, and vice-versa)
What issue do females have with having two X chromosomes?
Twice as much X mRNA transcription.
What do mammals do when they have twice the mRNA transcription (due to having two X chromosomes)?
Inactivate one of the two X chromosomes.
What are inactive chromosomes called?
Barr Bodies
When a random X chromosome is inactivated and mRNA transcription is blocked, what is the phenotypical result?
Genetic "mosaic"
Example: calico female cats
What if allele is not really dominant or recessive?
Incomplete dominance
What is the term for a heterozygote that has a phenotype that is an intermediate between that of both homozygotes?
Incomplete dominance.
Example: RR = Red
Rr = Pink
rr = White
Different carbohydrates on blood cells (A, B, AB, O) is an example of what?
When different alleles give different dominant traits; both affect the phenotype in a separate, distinguishable way, this is called?
What is the term for the event when there are different genes that control the same phenotype, as in mouse color (black, brown, white)?
Epistasis (different variations of 9:3:3:1)
When two genes are on the same chromosome they are called?
Linked genes
What are the two types of offspring when there are linked genes?
1) Parent-type offspring
2) Recombinant (nonparental-type) offspring
How are wild-type traits distinguished from mutation phenotypes in nomenclature?
Wildtype is identified with a + superscript.
What are parent-type offspring (as seen with linked genes)?
Offspring that look like parents' genotype and phenotype.
What are recombinant (non-parent-type) offspring (as seen with linked genes)?
Offspring that have different combinations of the genes than their parents.
What occurs during crossing over?
When linked genes are recombined with parts of homologous chromosomes.
When does crossing over occur?
Meiosis I, when the homologous chromosomes are lined up next to each other.
What is the name of the site of crossing over (the arm that recombines)?
What are a pair of homologous chromosomes called, as seen during Meiosis I?
What does crossing over achieve?
More variability in offspring; recombinant offspring.
What influences the rate of crossing over?
Distance between genes on chromosome (rarely on adjacent genes; more likely on distant genes).
Distance in centimorgans =
% of offspring with non-parental genotype
What is the name of the error in meiosis when chromosomes do not assort themselves properly (end up with gametes with an extra chromosome, or a missing chromosome)?
What are non-Mendelian inheritance issues?
1) Non-disjunction
2) Genes in semi-autonomous organelles (mitochondria & chloroplasts)
3) Imprinting
4) Non-DNA information (prions)