Quiz 1 (Modules 1 and 2, Slides 1-4) Flashcards
(76 cards)
1
Q
Define the term genome
A
a complete set of genetic instructions for any organism
2
Q
List the three major divisions of genetics and explain what each includes
A
Transmission genetics (classical genetics)
Molecular genetics
Population genetics
3
Q
Transmission genetics (classical)
A
Study of genetics of individual organisms
Basic principles of heredity and how traits are passed from one generation to the next
(Focuses on the individual organism)
4
Q
Molecular genetics
A
Studies of the chemical nature of a gene of individual organisms
How genetic information is encoded, replicated, and expressed
Focus on the molecular genetics of the gene
- its structure, organization, and function
5
Q
Population genetics
A
Study of the group of genes found in a population
Studies the genetic composition of populations
How genetic composition changes geographically and with the passage of time (includes evolution)
Focus is on the group of genes found in a population
6
Q
Describe common features of most model genetic organisms and explain model organisms why are useful for scientists
A
Common characteristics of model organisms:
Short generation time
Production of numerous progeny
The ability to carry out controlled genetic crosses
The ability to be reared in a laboratory environment
The availability of numerous genetic variants
An accumulated body of knowledge about their genetic systems
7
Q
Give a definition of a gene
A
unit of information that determines genetic characteristics.
The exact definition depends on the context
8
Q
Explain the relationship of genes and alleles
A
Different versions of the same gene are called alleles
Alleles differ in their DNA sequence
Different alleles result in rabbits with fur that is brown, white, black, or chinchilla.
9
Q
Explain the difference between phenotype and genotype.
A
Genotype: specific alleles (version of a given gene) that an individual has
- determined by the sequence in that individual’s DNA
Phenotype: the observable traits of an individual
- The phenotype of an individual is determined by their genotype
- Proteins are the links between genotype and phenotype
10
Q
State the “Central Dogma” of biology
A
gene expression is often referred to as the Central Dogma of Biology
11
Q
The order of the steps of gene expression in eukaryotic cells (like you did in the Central Dogma activity)
A
DNA, RNA, Protein
12
Q
Explain the relationship between genes and chromosomes
A
- Genes are located on chromosomes
- Genes are stretches of DNA located on chromosomes
Each chromosome contains a large number of genes - Every gene is located at a specific place on a specific chromosomes
13
Q
Explain what homologous chromosomes are
A
The two chromosomes in a pair
14
Q
Explain the basic characteristics of the genetic code
A
the set of rules that determine which codons code for WHICH amino acids
15
Q
the triplet nature of the genetic code
A
Set of 3 nucleotides that encodes a single amino acid
16
Q
the meaning of the term codon
A
a triplet RNA code
17
Q
that the code is degenerate, and what that means
A
(it is redundant): each amino acid encoded by more than one codon
18
Q
that the code is unambiguous, and what that means
A
each codon codes for one amino acid
19
Q
that AUG is the start codon
A
- AUG marks the start of protein (when correct sequences are upstream) AND
- AUG codes for also codes for one of the amino acids (Met) So: all polypeptide chains start with Met
- But: AUG also codes Met when it is inside coding region of a gene
20
Q
that there are stop codons and understand why they work
A
There are 3 Termination (stop) codons:
UAA
UAG
UGA
The termination codons do not code for any amino acids
21
Q
If given a sequence of RNA and a genetic code, be able to say the amino acid sequence encoded by that stretch of RNA
A
Use the genetic code in order to decipher it
22
Q
Define, and explain the different effects of, somatic mutations and germ-line mutations
A
Germ-line mutations: From an individual to subsequent generations
- Mutation occurs during meiosis; results in change in genome of sperm or egg cell
Somatic mutations: From a cell to its descendants
- Mutation occurs during mitosis; results in change to somatic (body) cells
23
Q
base substitutions
A
Mutation on which only a single nucleotide is changed
- Base substitutions are also referred to as a point mutation
Base substitutions can cause (a) missense: One amino acid is changed
(b) nonsense: Protein is shortened (premature termination of translation)
(c) silent mutations: Does not change amino acid sequence
24
Q
insertions
A
mutation in which one or more nucleotides are added to a sequence
25
deletions
mutation in which one or more nucleotides are deleted from a sequence
26
expanding nucleotide repeats
A type of mutation in which a set of tandemly repeated sequences replicates inaccurately to increase the number of repeats.
27
For point mutations: missense
Changes a sense codon into a different sense codon, resulting in the incorporation of a different amino acid in the protein
28
nonsense
Changes a sense codon into a nonsense (stop) codon, causing premature termination of translation
29
silent
Changes a sense codon into a synonymous codon, leaving the amino acid sequence of the protein unchanged
30
neutral
Changes the amino acid sequence of a protein without altering its ability to function
31
loss-of-function
Causes a complete or partial loss of function
32
gain-of-function
Causes the appearance of a new trait or function or causes the appearance of a trait in inappropriate tissue or at an inappropriate time
33
lethal
Causes premature death
34
For insertions and deletions: frameshift mutations vs. in-frame mutations
Frameshift mutation: Change reading frame
If reading frame is changes, all (or nearly all) the amino acids after that insertion/deletion are different
In-frame mutation: when insertions/deletions are multiples of 3
will add or delete amino acid(s) but will not change reading frame
35
If given two sequences of DNA, one wild-type and the other with a mutation, be able to state if the mutation is:
base substitutions, insertion or a deletion
For a base substitution, if given a genetic code, be able to state whether it is a missense, nonsense, or silent mutation
For an insertion or a deletion, state whether it is a frameshift mutation or a in-frame mutations
36
State the three Domains, and which type of cell (prokaryotic cells or eukaryotic cells) each domain has
Bateria: prokaryotic cells
Archea: prokaryotic cells
Eukaryota: eukaryotic cells
37
Prokaryotic cells:
the location of the chromosome(s) relative to the ribosomes
whether chromosomes are linear or circular
whether there are usually one chromosome or multiple chromosomes
whether they have organelles
Both prokaryotic and eukaryotic cells:
- Have hereditary information encoded by sequence of DNA
- DNA genome is located on chromosome(s)
- Transcribe genetic information from DNA to RNA
- Translate genetic information from RNA to protein on ribosomes
Eukaryotic cells have nucleus; prokaryotic cells do not
Linear
In prokaryotic cells, chromosomes are located in a region of the cytoplasm called the nucleoid
- So DNA and ribosomes are in same place
Prokaryotic cells: much less genomic DNA than eukaryotic cells
- whole genome usually contained in one, circular molecule
Prokaryotic cells is genomic DNA is less organized
- Bacterial genomic DNA: not complexed with histones
- Archaea genomic DNA: complexed with some histones
Two organelles contain their own DNA:
. Mitochondria and chloroplast
- Both are believed to have been derived from prokaryotes
- Both have circular DNA genome
Viruses: neither prokaryotic or eukaryotic
38
Eukaryotic Cells:
the location of the chromosome(s) relative to the ribosomes
whether chromosomes are linear or circular
whether there are usually one chromosome or multiple chromosomes
whether they have organelles
Both prokaryotic and eukaryotic cells:
- Have hereditary information encoded by sequence of DNA
- DNA genome is located on chromosome(s)
- Transcribe genetic information from DNA to RNA
- Translate genetic information from RNA to protein on ribosomes
Eukaryotic cells have nucleus; prokaryotic cells do not
Circular
In eukaryotic cells, chromosomes are located inside the nucleus
- Since ribosomes are outside the nucleus (in RER and in the cytoplasm), DNA is separated from ribosomes
Eukaryotes cells: much more genomic DNA
- genome present in multiple, linear DNA molecules
Eukaryotic genomic DNA is very organized
present as a complex with proteins called histones
In eukaryotes, DNA is found complex with histone proteins
. Histones allow DNA to be:
- Rather compact all the time
- Very compact during mitosis
This DNA and histone complex is called chromatin
Viruses: neither prokaryotic or eukaryotic
39
Describe the basic characteristics of viruses, including the fact that they can have either DNA or RNA genomes
. Viruses are not cells:
- are microscopic biological agents
. Viruses are very simple
- Just made up of genome surrounded by a protein coat
. Genome can be DNA or RNA
. Since viruses are so simple, can’t reproduce by themselves
. Viruses are intracellular parasites; life cycle includes
- Enter cells
- Use that cell’s proteins to transcribe and translate
. Also reproduce their genome
- Genome and proteins assemble
- New virus leaves infected cells; infect other cells
40
Explain the basic steps in binary fission, and state that binary fission is the way that prokaryotes reproduce
. Cell division in prokaryotes: binary fission
- Simple division of chromosome and cell contents
. Have single circular chromosome
- Is replicated and separated via origin of replication
. High rate of replication
1. A prokaryotic cell contains a single circular chromosome made up of double-stranded DNA.
2. As the chromosome replicates, the origins segregate to opposite sides.
3. The origins are anchored to opposite sides of the cell.
4. The cell divides. Each new cell has an identical copy of the original chromosome.
41
Describe what a chromosome is
in complex with histones
DNA is wrapped around histones, folded and condensed
When cells duplicate, become more highly condensed
42
Describe, and explain the function of, the following terms: chromatin
DNA is found complex with histone proteins
Histones allow DNA to be:
Rather compact all the time
Very compact during mitosis
This DNA and histone complex is called chromatin
Chromatin condenses, chromosomes become visible
Sister chromatids joined at the centromere
43
homologous chromosomes
The two chromosomes are like in size and structure
Called homologous chromosomes
also referred to as homologous pairs
Homologous chromosomes:
Are the same length and staining pattern
Have the centromere in the same position
Have genes for the same inherited characteristic on the same place (locus) on the chromosome
are NOT identical, since may have different alleles
44
sister chromatids
identical chromosomes
Made when DNA replicates
are attached to one another
45
centromeres
appears as constricted point in chromosome
Present on all chromosomes
Place on chromosome where microtubules bind to the chromosomes and pull them apart duding mitosis
Each chromosome only has one centromere
Has a characteristic position in different chromosomes
46
kinetochores
Spindle fibers attach to chromosomes on the kinetochore
Kinetochore: multiprotein complex that assembles on centromere
Correct attachment of the spindle microtubules to the kinetochore is critical for proper division of chromosomes
47
Be able to explain the difference between homologous chromosomes and sister chromatids.
Homologous chromosomes: are NOT identical
Have same genes on chromosomes, BUT
Some genes have different sequence (are alleles)
Sister chromatids: identical chromosomes
Made when DNA replicates
are attached to one another
48
State the ways that the two members of a pair of homologous chromosomes are similar, and in what ways are they different.
Homologous chromosomes:
Are the same length and staining pattern
Have the centromere in the same position
Have genes for the same inherited characteristic on the same place (locus) on the chromosome
are NOT identical, since may have different alleles
49
Identify which cell types are haploid and which are diploid.
Diploid cells:
Two sets of genetic information
2 copies of each homologous pair
Haploid cells:
One set of genetic information
1 copy of each homologous pair
50
Outline the important events that occur in each of the stages of the cell cycle in eukaryotes.
For interphase:
State the basic events of each of the three stages of interphase (G1, S, and G2)
interphase: Time when cell prepares for division
Makes proteins necessary for duplication
Synthesizes new copy of DNA
Duplicated organelles and chromosomes
~95% of time
G1 phase (first gap): Cells grow, makes protein required for DNA replication, start to duplicate organelles
Toward end of G1 phase:
Cell “decides” whether to
1. Replicate DNA and continue through cell cycle OR
2. Enter a resting state (G0)
S phase:
Cell replicates DNA (and grows)
G2 phase (second gap):
Cell grow, make proteins necessary for division of chromosomes (mitosis) and division of cells (cytokinesis)
51
State what occurs when a cell goes into a quiescent state (G0)
Stable, nondividing period of variable length.
52
For mitosis and cytokinesis
State the major events that occur during prophase, prometaphase, metaphase, anaphase and telophase.
Prophase: Chromatin condenses, chromosomes become visible
Sister chromatids joined at the centromere
Start to form framework from microtubules called mitotic spindle
Will become the microtubules used to separate sister chromatids
Prometaphase: Nuclear membrane disappears
Spindle microtubules enter nuclear region
Microtubules from each end (centrosomes) attach to kinetochore of ONE of the sister chromatids
Metaphase: Microtubules move sister chromatids until they align in a plane in a center of the cell
metaphase plate
At end of metaphase is spindle-assembly checkpoint; ensures that each chromosome is
aligned on the metaphase plate
attached to spindle fibers from opposite poles.
Attachment to both sides: determined by tension sensed at kinechore
Anaphase: Connections between sister chromatids are broken
Separated chromatids are then pulled by the spindle to opposite poles of the cell.
Are now considered separate chromosomes
Telophase: Chromosomes arrive at spindle poles
Nuclear membranes reform
Chromosomes relax
In many cell types, cytokinesis occurs at same time as telophase
53
If you are given a diagram or description of a cell, be able to state whether it is in interphase, prophase, metaphase, anaphase, or telophase.
1. interphase
2. prophase
3. prometaphase
4. metaphase
5. Anaphase
6. Telopahse
54
Describe what cytokinesis is and when it occurs during the cell cycle
Cytoplasm divides; cell wall forms in plant cells. Occurs during M phase
55
State how many cells are present at the end of mitosis, and whether the cells are genetically identical or different.
At the end of mitosis, the two daughter cells will be exact copies of the original cell. Each daughter cell will have 30 chromosomes.
56
Explain the role of cohesin during the cell cycle, including stating the name of the enzyme that breaks it down and when in the cell cycle that enzyme is active.
Cohesin: a protein that holds the chromatids together
During anaphase of mitosis and anaphase II of meiosis, cohesin breaks down
By enzyme (separate)
57
State the three major checkpoints during the cell cycle, and describe what occurs at each checkpoint.
Spindle-assembly: Makes certain each chromosome is aligned on the metaphase plate and attached to spindle fibers from opposite poles.
G1/S: Makes certain cell has all the enzymes for making DNA
G2/M: Makes certain DNA is fully replicated and undamaged
58
Predict the number of DNA molecules found in a cell at different stages of the cell cycle (like the problems in Sapling problems and the problem-solving and review sheet).
Before S phase: (when DNA has NOT been replicated):
# of DNA molecules = # of chromosomes (no sister chromatids)
After DNA has been replicated (S phase):
# of DNA molecules = twice (2x) # of chromosomes
since there are two sister chromatids for every chromosome
Has 2X amount of DNA
After cytokinesis: back to 1X DNA molecules and 1X DNA
To determine the number of DNA molecules and amount of DNA:
If DNA has been replicated AND are still attached (after S phase but before anaphase)
# of DNA molecules = twice (2x) # of chromosomes
since there are two sister chromatids for every chromosome
Has 2X amount of DNA
- After cytokinesis: returns to normal number of molecules and amount of DNA
59
State what is meant by the following terms: diploid cells
Diploid cells: cells with 2 copies of each chromosome
Diploid cells are referred to as 2n
Where n is the number of different types of chromosomes
60
haploid cells
haploid: they have only one copy of each pair of chromosomes
So are referred to as “n”
61
gametes
Gametes are reproductive cells: eggs and sperm cells
Gametes are haploid:
they have only one copy of each pair of chromosomes
So are referred to as “n”
Gametes (sperm and eggs) are the way that genes are passed to the next generation via reproductive cells
62
zygote
Fertilized egg is called a zygote
Zygotes are diploid (2n)
have one copy of each chromosome pair from each parent
Zygotes undergo multiple rounds of mitosis
eventually become an adult organism
63
fertilization
Fertilization: the union of gametes (the sperm and the egg)
when a sperm and egg are fused together
64
The number of cell divisions that occur in one meiotic division.
1 cell division
65
The number of cells made from one cell during a cycle of meiosis.
4 cells
66
During which division is the chromosome number reduced in half.
Meiosis
67
What synapsis is.
the fusion of chromosome pairs at the start of meiosis
68
During what stage does synapsis of homologous chromosomes occur.
Meiosis I: Prophase I
69
What crossing over is and when it occurs.
Occurs in Prophase I
Crossing Over: Separates genes that are on the same chromosome
Occurs during prophase
70
What the result of crossing over is.
Make hybrid chromosome:
part from one parent, part from the other
71
State the similarities and differences between mitosis and meiosis, including:
the number of cells produced
whether homologous chromosomes synapse
whether resulting cells are haploid or diploid
whether resulting cells are genetically identical or different.
Mitosis:
No paring of homologous chromosomes
1 cell division
2 cells produced
Progeny cells have the same number of chromosomes
Progeny cells are genetically identical to parent cell
Meiosis:
Homologous chromosomes pair
2 cell divisions
4 cells produced
Progeny cells have half the number of chromosomes
Progeny cells are genetically different from parental cell
72
State the stages of meiosis, including the type and number of chromosomes that are present during at each of these stages.
Prophase: 46
Metaphase: 46
Anaphase: 92
Telophase: 92
73
Define the terms diploid and haploid, and state which types of the cells in the body are diploid and which are haploid
If given the amount of DNA in pg in normal, diploid cells of a specie, be able to predict:
the amount of DNA present in the haploid cells
the amount of DNA present at different steps in meiosis (like in the in-class activity)
Diploid cells: cells with 2 copies of each chromosome
All of the somatic (body) cells in our bodies are diploid
haploid: they have only one copy of each pair of chromosomes
So are referred to as “n”
Gametes are reproductive cells: eggs and sperm cells
Gametes are haploid
74
Explain the two ways that genetic variation is generated during meiosis, including why meiosis produces random combinations of chromosomes, with each combination equally likely.
Independent Assortment of Chromosomes
Separates genes that are on different chromosomes from one parent
Occurs during and just after metaphase
Crossing Over
Separates genes that are on the same chromosome
Make hybrid chromosome:
part from one parent, part from the other
Occurs during prophase
75
Be able to predict what would happen if any of these three proteins did not function correctly at a given time during meiosis (like in the problem-solving and review sheet)
Explain the role of cohesin, separase, and shugoshin in determining when sister chromatids separate during mitosis and meiosis.
Cohesin: a protein that holds the chromatids together
During anaphase of mitosis and anaphase II of meiosis, cohesin breaks down
By enzyme (separase)
Separase: a protein that cleaves cohesin molecules which hold the sister chromatids together
When active, sister chromatids separate
Shugoshin protects cohesin at centromere during anaphase I
-Homologous chromosomes separate, not sister chromatids
Shugoshin breaks down at the beginning of Meiosis II
- Allows sister chromatids to separate
76
State the difference between spermatogenesis and oogenesis in terms of the number of cells produced.
spermatogenesis
Produce sperm
oogenesis
Produce eggs
