Test 2 Flashcards
When the glucocorticoid hormone binds, what happens?
The glucocorticoid receptor activates transcription of several genes involved in the glucocorticoid response to stress/exercise.
Transcription initation complex consists of:
Transcription regulators
General transcription factors
RNA polymerase
MyoD is a ________ _________ that commits cells to become __________.
Transcription regulator, myoblasts
________ can become myoblasts due to MyoD (immunostained w/ antibodies that detect muscle -specific proteins) expression.
Fibroblasts
Methylated sites on cytosine can ____ ______ gene expression. This is mechanism for inheritance of patterns if gene expression.
Turn off.
What is the germ line? Can that mutation be passed on to offspring of the individual?
The cell lineage in a multicellular organism that contributes to the formation of a new generation by producing gametes.
-yes, the mutation does not affect the individual in which it occurred but it is heritable.
What is a somatic cell? If a mutation occurs in a somatic cell, will it be passed on to offspring of the individual?
- body cell
- only the progeny of the cell will be affected in the individual in which the mutation occurred.
What are the genetic changes that contribute to gene alteration and genome evolution?
- Mutation within a gene
- mutation in regulatory region
- gene duplication
- Mobile genetic elements
- Horizontal transfer
Mutation within a gene results in_____.
Altered product.
A mutation in a regulatory region results in an______.
Altered expression.
Genre duplications result in_____.
Beginning of a gene family.
Horizontals transfer results in_______.
Gene acquisition.
The presence of different regulatory DNA sequences in closely related spp results in:
The use of different developmental pathways.
What are gene families? And how are the related genes related ?
Groups of genes that originate by duplication from a common ancestor.
Family members are similar in structure and function.
Describe the global gene family.
- multiple diff. genes code for hemoglobin subunits.
-diff. members are expressed during diff life stages.
-include pseudogenes
-
What is a heme group?
Iron containing molecule in globin in subunit that contains the binding site for Oxygen.
What does hemoglobin transport in the circulatory system?
CO2 and O2
What and how many subunits does the adult hemoglobin contain?
2 alpha
2 beta
What are the difference between the different globin proteins?
They have different affinities for O2.
Short repeated sequences within homologous chromosomes cays what?
Misalignments and unequal crossing over which results in gene duplication
What are short repeated sequences?
Non coding conserved sequences that are scattered through out the genome.
What affect does unequal crossing over have on chromosomes?
Altered size and genetic content.
- one chromosome has an extra copy of the gene
- one chromosome lost the gene.
X. tropicalis has a ________ genome. (Frog)
Diploid
X. lavis has a ________ genome as a result of of duplication of the whole genome.
Tetraploid
The doubling of a genome results because of what? And is the doubling of the gene passed on?
Results if a germ cell fails to divide after DNA replication.
-may be passed on to games and eventually to the progeny.
What can mediate gene rearrangement?
The transposition of eukaryotic Mobile genetic elements.
Describe exon transposition
When similar mobile genetic elements insert near each other on the same chromosome, a transposition mechanism may use the ends of the 2 different elements, resulting in transposition of the entire segment of the chromosome between 2 mobile elements.
If the segment includes an exon, it’s insertion would create a new version of that gene.
The transposition of eukaryotic mobile genetic elements can alter_______, which can alter the tissue-specific pattern of gene expression.
Regulatory sequences.
In fruit flies, what gene is ectopically expressed in the head as a result of the a mobile genetic element (p-element) inserting into this gene’s regulatory sequence?
Antennapedia
Antenna are transformed into legs.
What is homeotic transformation?
One body part is replaced by a body part normally found in another region.
What is conjugation? And what is its result?
Conjugation is the transfer if genetic info (via a plasmid) from one cell to another through a sex pilus.
The result is genetic recombination without reproduction.
Fibroblasts and myoblasts are both derived from the _________ _________.
Embryonic mesoderm.
What are three mechanisms of inheritance of patterns if gene expression?
- +feedback loop involving transcription regulators.
- Preservation of covalent histone modifications and chromatin condensation patterns.
- Preservation if DNA methylation patterns.
What is passed on to daughter cells in a positive feedback mechanism for inheritance of gene expression?
Transcription regulators.
What is the function of tissue-specific histone binding enzymes?
This enzyme is preserved through out cell devision and is passed on to daughter cells. The enzyme restores the parent pattern of histone modification and chromatin condensation.
What happens when specific GC sequences are methylated?
These methylated sites turn off gene expression by attracting proteins that block transcription.
After DNA is replicate which strand is the only one methylated?
Parent/template
What enzyme recognizes already methylated GC sequences and catalyzes the methylation of corresponding GC sequences in the new DNA strand?
Maintenance methytransferase
How is the DNA methylation pattern preserved?
Maintenance methyl transferase is passed on to the daughter cells.
What transcription regulator in Drosphila controls the expression of many different genes and can also induces the expression of additional transcription regulators including itself?
Eyless
The Eyeless gene in fruit flies is similar to what gene in mice and humans?
Pax-6
How do humans develop aniridia?
Heterozygous for pax-6 mutation
What is a phospholipid?
Polar (hydrophilic) head group and non-polar (hydrophobic) hydrocarbon tails (fatty acids).
In the fluid mosaic biological membrane in what way do lipids and proteins diffuse?
Laterally.
The cellmbrane is fluid, it’s course parts can move in what ways?
Flexion, rotation,
Identify the structures if a phospholipid:
- Hydrophobic head–> polar group, phosphate, glycerol
2. Two hydrophobic fatty acid tails.
Describe the structure of cholesterol:
- Polar head group- OH
2. Nonpolar groups: steroid ring structure and hydrocarbon tail.
How does cholesterol function?
Modulated membrane fluidity.
- high temps, cholesterol restrains movement. (Maintains stability)
- at low temps, cholesterol prevents right packing of fatty acids. (Maintains fluidity)
Glycolipids are ways found where? And and do what?
They are always found in the outer layer of the membrane.
They are cell identity markers.
Charged phospholipids (phosphatidylinsotol and phosphatidyserine) are always found where? And what is an exception?
Inner layer of the membrane.
Except for when an enzyme is activated to flip the charged particle to result in cell death.
What are the protein components of the cell membrane?
Transporters –> carrier proteins and ion channels
Anchors–> integrins
Surface receptors–> hormone receptors
Enzymic proteins–> tyrosine kinases
Glycoproteins, proteoglycans, and glycolipids form what?
- Protective carbohydrate layer
They are cell identity markers.
What surface receptors do endothelial cells express in responses to signals from infected tissue?
Lectin
Small hydrophobic molecules that can diffuse across a membrane:
O2, CO2, N2, benzene
Small uncharged molecules that can diffuse across a biological membrane:
H2O, glycerol, ethanol
Large uncharged polar molecules that can’t diffuse across a membrane:
Amino acids, glucose, nucleotides
Ions that can’t diffuse across a membrane:
H+, Na+, HCO3-, K+, Ca2+, Cl-, Mg2+
In the ear, what collects sound waves? And were are the sound waves concentrated?
-they are collected in the auditory canal and concentrated at the tympanic membrane
The tympanic membrane is also known as:
The ear drum
After concentration, the sound waves are then relayed through what?
Through three auditory ossicles: malleus, incus, and stapes.
Vibrations from the auditory ossicles are received by the _______ through the_____________.
Cochlea, oval window.
What is the oval window?
The interface between the air in the middle ear and the fluid mosaic in the cochlea.
Sound waves travel as pressure waves though the _____ ____ inside the _____ _____, then return through the tympanic duct and are dissipated through the ______ ________.
Perilymph fluid,
Vestibular duct,
Round window
How does the neurotransmission of hearing impulses begin?
With the opening of mechanically-gated potassium channels.
Which ion flows into the sterocillia thereby initiating the hearing sensation?
K+
What is membrane potential? How is it established?
(Vm)The voltage across the membrane
It’s established by the charge difference between the two sides of the membrane.
Measured in mV.
When a nerve is at rest, what is the membrane voltage at? Are the voltage gated Na+ channels open or closed?
Membrane voltage: -80 mV (cell is -)
Channels are closed.
Durning the rising phase of a nerve cell, what happens?
A depolarizing stimulus current causes the membrane to reach the threshold potential (-60 mV) which opens the Na+ channels. Leading to action potential.
What is action potential?
When and influx of Na+ Channels causes the membrane to depolarize to +40 mV
What do voltage-gate Na+ channels become inactivated?
At the peak of action potential 40mV
A membrane returns to resting potential due to what?
The opening voltage gate k+ channels and the activity of the Na/K pump. Allows K to leave the cell.
What happens at the end of the falling phase?
Voltage gate Na and K channels close.
The phosphorylation of the Na/K pump causes what?
A conformational change that releases the Na+ ions to the outside cell.
Dephosphorylation of the of the Na/K pump causes what?
The return of the original conformation and the release of K+ ions inside the cell.
What causes cystic fibrosis?
A point mutation in an ATP-dependent Cl- ion transporter that alters the ionic gradients of several types of cells, which effects the cells osmotic balance.
Mutations cause disrupt the folding of the CFTR protein
CFTR protein
Cystic fibrosis transmembrane conductance regulator.
Where do all reactions of glycolysis occur?
Cytoplasm
What is substrate level phosphorylation?
The transfer of a phosphate from a sugar intermediate to ADP.
What happens when glucose is transformed to glucose 6-phosphate?
ATP is consumed and hydrolyzed and glucose is phosphorylated.
Describe what takes places starting with glucose6-phosphate going to fructose 6-phosphate?
Isomerizarion of G6P
Describe the reaction to obtain fructose 1, 6-bisphosphate
Phosphorylation of F6P at C1. ATP is consumed. Unreversible.
How are dihydroxyacetone phosphate and glyceraldehyde 3-phosphate obtained?
From the cleavage of FBP. Reversible.
DHP needs to undergo isomerization to become GAP.
Describe the reaction to get from glyceraldehyde 3-phosphate (GAP) to 1,3-bisphospopholycerate.
GAP is oxidized, 2NAD+ reduced to 2NADH, P is attached to C1. Reversible
Describe the reaction from 1-3BPG to 3-phosphoglycerate:
P is transferred from BGP to ADP, 2 ATP are synthesized by substrate level phosphorylation. Reversible
Isomerization of 3PG yields what? Describe the free energy.
2- phosphoglycerate low free energy. Reversible.
Dehydration of 2PG yields what?
Phosphoenolpyruvate. High energy. 2 H2O are removed. Reversible.
Describe the creation of puruvate from the previous molecule.
Transfer of P from PEP to ADP. 2 ATP are synthesized by substrate level phosphorylation.
Net yield of glycolysis:
2ATP+2NADH
What happens to pyruvate in muscle cells in the absence of oxygen?
2 pyruvate molecules are reduced by 2 NADH—> 2 lactate molecules and NAD+
What happens to pyruvate in yeast?
2 CO2 are removed—> 2 acetaldehyde
2 acetaldehyde+ 2 NADH–> 2ETOH +NAD +
When O2 is present, where are pyruvate and NADH transported?
The mitochondria.
What happens to pyruvate after it has been taken into the mitochondria?
Pyruvate is oxidized and converted to acetyl coenzyme A and enters the citric acid cycle.
What is oxidative phosphorylation? And what powers it?
The electron transport chain. NADH
Where in the mitochondria does the oxidation of pyruvate and the citric acid cycle occur?
The matrix
What occurs in the inner membrane of the mitochondria?
Electron transport chain and oxidative phosphorylation.
How is acetyl CoA produced?
Pyruvate+ CoA –> 2acetyl CoA+ CO2
Condensation
CO2 is removed via hydrolysis
acetyl CoA(2C)+ Oxaloacetate(4C)–>
- Citric acid (6C)
Condensation and citrate synthesis.
Hydrolysis removes CoA which drives the reaction forward.
2 (cac). Citric acid + isomerization–>
Isocitrate
- Isocitrate (6C) + NAD+——>
Alpha-ketoglutarate (5C) + CO2+ NADH+ H
- Alpha-ketoglutarate+ CoA + NAD+ —>
Succinyl CoA + CO2 + NADH
- Succinyl CoA+ h2o+ P+ GDP–>
Succinyl (4C) + GTP + ATP synthesis
- Succinate (4C) + FAD —>
Fumerate (4c) + FADH2
- Furamate+ h2o–>
Malate (4C)
- Malate + NAD+ –>
Oxaloacetate ( 4C)
Re enters the cycle.
Yield of the citric acid cycle 2x
4CO2
6NADH
2FADH2
2ATP
When H+ flows back into the matrix of the mitochondria, what happens?
ATP synthesis
What powers the H+ pumps?
Oxidation NADH and FADH2
NADPH
Electron carrier in photosynthesis
