Test and Quiz Questions Flashcards
(122 cards)
1
Q
Darwin is famous for
A
explaining HOW evolution could happen
2
Q
Why is genetic variation crucial for evolution?
A
It is the source material for natural selection
3
Q
Define parsimony
A
the smallest amount of change
4
Q
What is disruptive selection?
A
The organisms with extreme phenotypes have the highest fitness
5
Q
What is the modern definition of evolution?
A
Change in allele frequencies in a population over time
6
Q
What postulates led to Darwin’s idea of natural selection?
A
- Offspring are VARIABLE
- Offspring RESEMBLE their parents
- More offspring are PRODUCED than can survive
- Those that survive are a NON-RANDOM sample
7
Q
What is a homeobox?
A
The region of DNA in a hox gene that codes for a portion of the protein that binds to DNA
8
Q
What happens when a histone tail is modified?
A
Chromatin structure is affected which affects gene expression
9
Q
In general, when cytosine bases in CpG islands are methylated:
A
Transcription is repressed
10
Q
X inactivation is caused by the accumulation of what?
A
Noncoding RNA produced by the Xist gene, which coats the X chromosome
11
Q
A mutation occurs that causes a defect in the development of skeletal muscle. The mutation would likely have occurred where?
A
Mesoderm
12
Q
How is position along the anterior-posterior axis of an embryo determined by the protein bicoid?
A
Its concentration in different regions
13
Q
An activator protein combines with a small molecule and undergoes a change in shape that alters its binding affinity to DNA. This change is shape is called what?
A
Allosteric affect
14
Q
What would happen if the promoter to the lac operon was mutated?
A
RNA polymerase could not bind
15
Q
What is the function of B-galactosidase?
A
To cleave lactose into its monomer sugars: glucose and galactose
16
Q
Gurdon’s nuclear transplantation experiments with tadpoles support which hypothesis?
A
Differentiation its the result of genes being successively turned on or off over time
17
Q
Do individuals evolve?
A
No, individuals live or die, populations evolve over time
18
Q
Genetic variation in a population refers to what?
A
Multiple alleles within a gene pool
19
Q
What is one reason why mutations may be deleterious?
A
Because if a mutation changes the primary structure of a protein, the protein may no longer work
20
Q
A drought nearly causes a tree frog population to go extinct. Frogs that had slightly thicker skin survived in higher numbers than frogs with thinner skin. If skin thickness is a genetically based trait, how would you describe what happened?
A
Directional selection
21
Q
Why does ice float in liquid water?
A
Stable hydrogen bonds keep water molecules of ice further apart than water molecules of liquid water
22
Q
Nitrogen (N) is more electronegative than hydrogen (H). Which of the atoms have a partial positive/negative charge in NH3?
A
Each hydrogen atom is slightly positive. Each nitrogen atom is slightly negative.
23
Q
What distinguishes amino acids from one another?
A
The composition of their side chains (R groups)
24
Q
Suppose you discovered a new amino acid. It’s R group contains only hydrogen and carbon atoms. Predict the behavior of the amino acid
A
It is hydrophobic
25
Which characteristics do all life forms share?
- Complexity
- Ability to respond to the environment
- Ability to reproduce
- Capacity to evolve
26
Summarize the cell theory?
All organisms are made of cells, all organisms come from preexisting cells
27
If a DNA sample is 10% thymine, what percentage is guanine?
40%
28
What about DNA's structure facilities copying?
The strands of the double helix are complimentary
29
How to bonds differ between adjacent nucleotides in the backbone of the DNA versus between complimentary base pairs?
Complementary pairs (adjacent bases of nucleotides) are hydrogen bonded. The backbone is covalent (phosphodiester) bonds
30
Draw a nucleotide
--
31
You get a paper cut. What kind of cell division occurs to help you heal?
Mitosis
32
How do two members of a pair of homologous chromosomes differ from each other?
They potentially have different alleles of the same genes
33
In the context of cell signaling, to what does the term ligand refer?
A signaling molecule that binds to a receptor
34
After the S phase of the cell cycle, what comprises a single chromosome?
- - Two sister chromatids
| - - Two double stranded molecules of DNA attached at the centromere
35
What type of transport is involved in the following: The action of sodium-potassium pumps moves sodium ions out of the cell and potassium ions into the cell, against their concentration gradients.
Active transport
36
What does 3n=6 mean?
There are three of each kind of chromosome
37
During the signal transduction process, the signal often triggers a signal cascade. For example, an activated receptor actives hundred of protein A. Each activated protein A activates hundreds of protein B and so on until a cellular response occurs. What purpose does a cascade serve?
The cascade serves to amplify the signal, so one activated receptor can have a significant response
38
The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on what?
The presence of the appropriate receptors on the cells of the target tissue or organ
39
Draw a cell membrane and use the following words to label it: polar, hydrophobic, hydrophilic, non polar, channel for facilitated diffusion, transmembrane protein, G protein coupled receptor, receptor kinase, saturated fatty acid tail, unsaturated fatty acid tail, signaling molecule nearby
---
40
Banded snakes are present in inland populations of water snakes, even though they are intensely selected against.. What accounts for the presence of banded snakes on the islands?
Gene flow
41
Mutation is the only evolutionary mechanism that does what?
introduces new genetic variation into populations
42
Large males fight each other and win more territorial contests than smaller males. What kind of selection is this?
Sexual selection via intrasexual selection
43
A farmer uses triazine herbicide to control pigweed on his field. For the first few years of treatment, the triazine works well and almost all the pigweed dies; but after several years, the farmer sees more and more pigweed. What explains this observation?
Only triazine resistant weeds survived and reproduced, so each year more pigweed was triazine resistant
44
If you choose one pair of human chromosomes, what do the two chromosomes have in common?
Length, centromere position, and similar (same genes) but not necessarily identical DNA sequences (different alleles)
45
What is the modern definition of evolution?
Change in allele frequencies in a population over time
46
What are the two main points the Darwin made in his book?
1) diverse groups of animals evolve from one or a few common ancestors
2) the mechanism by which this evolution takes place is natural selection
47
Why does the chromatin remodeling have to be the first step in gene activation in eukaryotes?
Eukaryotic DNA is highly packaged in condensed chromatin and inaccessible to transcription factors and RNA polymerase before remodeling
48
The muscle cells and nerve cells in a mouse look very different and serve very different functions. Why?
These cells express different genes
49
Which type of mana is present at greater levels at the anterior end of a Drosophilia embryo than the posterior end?
Bicoid mRNA
50
After fertilization, what process produces all subsequent cells in the adult human?
Mitosis
51
What is the name of the regulatory protein that controls the cell cycle?
Cyclin
52
What could cause uncontrolled cancer cell growth?
non-functional p53
53
Why is meiosis I known as the reductional division?
The first division is called the reduction division – or meiosis I – because it reduces the number of chromosomes from 46 chromosomes or 2n to 23 chromosomes or n (the cell goes from diploid to haploid)
54
When does crossing over occur in meiosis?
Prophase I
55
What is the function of primase?
Synthesis of a short RNA sequence during DNA replication
56
Adult humans are (....haploid, diploid etc)?
Haploid
57
DNA is synthesized through a process known as what?
Semi-conservative replication
58
Draw a 2n=6 cell at G1 and then at metaphase I of meiosis
---
59
What is the function of the endoplasmic reticulum?
Synthesizes proteins and lipids
60
Why do unsaturated fatty acids help keep a membrane more fluid at lower temperatures?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly
61
What is the main difference between diffusion and facilitated diffusion?
Facilitated diffusion uses a channel protein
62
Lipids that form membranes have what kind of structure?
Polar heads and non polar tails; the polar heads interact with water in and outside of the cell
63
If meiosis produces haploid gametes, how is the diploid number restored for those organisms that spend most of their life in the diploid state?
Fertilization
64
Prokaryotes divide via...?
Binary fission
65
What is a genotype?
The particular combination of alleles in any given organism
66
Mendel's experiments with garden peas differed from those of other plant breeders at the time in that Mendel did what?
Focused on true breeding lines and a small number of easily contrasted traits. Quantified results
67
A synonymous mutation has no effect on the phenotype because?
The mutation is such that the codon specifies the same amino acid
68
What is the current hypothesis explaining why large mammals get cancer much less often than humans?
They have more copies of the p53 gene
69
What events contribute to producing genetically variable offspring through sexual reproduction?
Crossing over, independent, assortment
70
How would genetic variation be affected if there was no independent assortment?
Gametes would either contain maternal or paternal chromosomes only
71
If a diploid cell has 24 chromosomes, how many chromosomes do each of its 4 daughter cells have?
12
72
Where do we find DNA in bacterium?
The nucleoid region
73
How do chromosomes move around in the cell during meiosis and mitosis?
Spindle fibers that attach to kinetochores
74
What does mitosis produce?
Two genetically identical cells
75
True or false: DNA polymerase separates the DNA double helix as it synthesizes a new polypeptide chain?
False!
76
What type of transport is involved in moving things against their concentration gradient?
Active transport
77
What is the function of adenylyl cyclase?
To form cyclic AMP
78
What is the sequence of steps n the eukaryotic cell cycle?
G1---> S ----> G2 ----> mitosis ----> cytokinesis
79
What is a kinase?
An enzyme that activates or inactivates other proteins by adding a phosphate group to them
80
Which type of diffusion functions to move LARGE molecules along their concentration gradient?
Facilitated diffusion
81
Different body cells can respond differently to the same peptide hormones because..?
A target cell's response is determined by the components of its signal transduction pathways
82
A true breeding strain is...?
Homozygous
83
In the context of cell signaling, to what does the term ligand refer?
A signaling molecule
84
Adrenaline from the adrenal glands is an example of what type of signaling?
Endocrine signaling
85
How are Okazaki fragments synthesized?
Using the lagging strand and synthesizing 5 prime to 3 prime
86
Why would the removal of the 5 prime triphosphate from the nucleotides used by DNA polymerase block the process of DNA synthesis?
The energy used to link one nucleotide to another would no longer be available
87
What occurs when a covalent bond forms?
Electrons in the valence shells are shared
88
The backbone of the DNA molecule is made up of what?
Alternating sugars and phosphate groups
89
An atom has an atomic number of eight and has six electrons in the valence shell. How many single covalent bonds would you expect to form?
Two
90
Prions are interesting because they have the same amino acid sequence as a normal protein, but a different what?
Shape
91
A covalent bond is likely to be polar when...?
One of the atoms sharing electrons is more electronegative than the other
92
Some proteins do not fold properly on their own after translation. These proteins require the assistance of which molecules?
Chaperones
93
What types of bonds are between complementary base pairs in DNA?
Hydrogen bonds
94
The fully folded structure of the a functional protein composed of a single polypeptide chain is referred to as the ____ structure.
Secondary
95
How is secondary structure stabilized?
By hydrogen bonds
96
____ are monomers of nucleic acids
Nucleotides
97
____ are monomers of proteins
Amino acids
98
What are enhancers?
A sequence of DNA to which transcription activator proteins bind
99
What would be the result of there was no 5 prime cap?
The ribosome would not recognize the 5 prime end, the initiation complex would fail to form, and translation would not occur
100
What does alternative splicing mean?
Different spliced forms of mRNA contain different combinations of exons
101
Which protein interacts directly with the stop codon?
Release factor
102
In eukaryotes, the AUG codon that starts translation is located where?
Adjacent to the Shine-Dalgarno sequence
103
What is an intron?
A DNA sequence that is part of a gene, is noncoding, and is removed during the processing of its mRNA molecule
104
If you made a change in the promoter sequence in the DNA that inactivates the promoter, what would happen at the RNA level?
The RNA polymerase would not be able to recognize and bind do DNA, so no RNA would be made
105
Translation is the process by which..?
Ribosomes synthesize protein from information in an RNA molecule
106
The discovery that DNA from killed virulent bacteria can transform live harmless bacteria into virulent from means what?
That DNA contains organisms that determines an organism's traits
107
Who was Rosalind Franklin?
The scientist who's X-ray diffraction picture of DNA helped solve its structure
108
What is a ribozyme?
an RNA with catalytic activity
109
What is the relationship between newly synthesized RNA molecules and the DNA template strand?
Complementary
110
What is a working definition of a gene?
A sequence of DNA that goes for a functional RNA molecule
111
What are the four main characteristics of life?
- - Complexity
- - Capacity to evolve
- - Capability to respond to the environment
- - Capability of reproduction
112
How does caffeine affect the kidneys?
Blocks receptors for ADH
113
A longer micro-sattelite region in prairie voles was correlated with what sort of behavior?
Increased social bonding behaviors
114
What are micro-satelitte sequences?
Series of nucleotide repeats, two to four bases long, that are repeated over and over
115
What is the relationship between the hypothalamus and the anterior and posterior lobes of the pituitary?
The hypothalamus communicates directly with the posterior pituitary via neurons and with the anterior pituitary through blood vessels
116
Steroid and peptide hormones have what in common?
They both travel through the bloodstream
117
Where do neurons communicate?
The synapse
118
Draw an axon where the membrane is at resting potential: indicate with +s and -s, the relative charges of different sides of the membrane and label channel proteins clearly. Then choose one part of the action potential and indicate what happens during that phase
---
119
Where is insulin produced?
Pancreas
120
What are the target tissues of insulin?
Liver and muscles
121
What is the result on the target tissues when insulin is secreted?
Glycogen is synthesized and blood sugar levels are reduced
122
What is myelin?
The sheath that cover neurons and speeds up nerve conduction
