Bio 211 > Unit 3: Topic 12 > Flashcards

Unit 3: Topic 12 Flashcards

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1
Q

What is a mutation?

A

Changes to the nucleic acid sequence (DNA/RNA). Which can be inherited (germline) or not (somatic).

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2
Q

Changes in the nucliec acid sequence can be small(_______ ______) or large(_________).

A

Gene Level
Chromosomal

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3
Q

Spontaneous mutations:

A

Naturally occurring mutations, mainly caused by replication errors.

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4
Q

What are the 2 types of spontaneous mutations?

A

Deamination of bases(C->U) and depurination(removal of the purine base from the DNA).

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5
Q

What are induced mutations?

A

Natural or artificial agents (mutagens) that causes mutations at a much higher rate than spontaneous. Replacing, altering, or damaging a base. So that it cannot base pair correctley.

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6
Q

Base analoges:

A

(Replace) Mimic bases and incorporates into DNA ( can cause mispairing during DNA replication).

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7
Q

Chemicals that cause mispairing:

A

(Altering) ex. alkylating and intercalating agents.

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8
Q

What are examples of damage to bases?

A

UV light thymine dimers, aflatoxin B-apurnic sites.

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9
Q

What are germline mutations?

A

Occur in gametes, and are heritable.

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10
Q

What are somatic mutations?

A

Occur in every cell but gametes, are not heritable. Mutation occurs i n a progenitor cell, and all sequential daughter cells.

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11
Q

What are small scale mutations?

A

Changes to one or few base pairs. 4 types; 1. Point mutation 2. Base substitution 3. Insertion 4. Deletion.

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11
Q

Sectors:

A

How Somatic mutations are expressed, size depends on time of mutation.

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12
Q

Point mutation:

A

A change at a single point on the DNA (substitution, deletion or insertion).

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13
Q

Base substitution:

A

Original nucleotide becomes a different nucleotide.

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14
Q

Insertion:

A

A nucleotide is added to the original sequence.

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15
Q

Deletion:

A

A nucleotide is removed from the original sequence.

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16
Q

What are the two types of base substituations?

A

1) Transitions: Purine-Purine or Pyrimidine-Pyrimidine.
2) Transversions: Purine-Pyrimidine or Pyrimidine-Purine.

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17
Q

What are the 4 effects that point mutations have on amino acid sequence of polypeptides?

A

1) Silent(synonymous mutation).
2) Missense(non-synonymous)
3) Nonsense
4) Frame shift

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18
Q

What is a silent mutation?

A

Codon change does not change the amino acid due to the degeneracy of the genetic code.

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19
Q

What is a missense mutation?

A

Codon change causes change to the amino acid sequence.

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20
Q

What is a Nonsense mutation?

A

Sense codon is changed for a stop/nonsense codon, resulting in a trunculated polypeptide. Impact depends on where mutation is.

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21
Q

What is a frame shift mutation?

A

Changes the reading frame of the mRNA due to insertion or deletion of nucleotides.

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22
Q

What is Sickle cell anemia?

A

A base substitution point mutation in the beta-hemoglobin gene. Transversion that results in a missense mutation that changes the 6th amino acid from glu to val.

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23
Q

What are the symptoms of sickle cell anemia?

A

Deficient gas exchange, clogged arteries, circulatory problems, higher risk of heart attack and stroke.

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24
What problems does the mutation in the beta-hemoglobin gene cause?
In low oxygen environments the beta subunit causes hemoglobin molecules to polymerize into long fibers that alter the shape of RBC's.
25
What are the 4 types of large scale chromosomal mutations?
1. Deletion(loss of genes) 2. Duplication/amplification (Increasing gene). 3. Translocation(Interchanging nonhomologous parts of chromosomes). 4. Inversion(reversing orientation of a segment of the chromosome).
26
Allele:
One of the many different forms of a gene, which can cause different phenotypes.
27
Gain of function(GOF):
Mutations that enchance gene function/expression.
28
Loss of function(LOF):
Mutations that reduce/eliminate gene function/expression.
29
Wild type:
Normal form of the gene found in nature or the standard lab strain.
30
The eukaryotic cell cycle:
Set of processes by which one cell grows and divides to make 2 daughter cells. Need to fully replicate DNA and organelles and properley segregate into daughter cells.
31
What are the 5 stages of the eukaryotic cell cycle?
1) Gap phases 2) S phase 3) M phase 4) Cytokenesis 5) G0
32
Gap phases(G1/G2):
Synthesis of proteins, RNA, Metabolites, other than DNA.
33
S phase:
Replication of DNA. Each DNA molecule is replicated independentley, following replication each DNA molecule exists as a pair of sister chromatids that are attached at the centromere.
34
M phase(mitosis):
Nuclear division
35
Cytokenisis:
Cell division.
36
Most adult humans are in __ permenantaly(_________+_____ cells) or semi-permenantaly(________ during injury.
G0 Nerve, muscle Liver
37
G0:
Resting stage.
38
Progression of the cell cycle depends on activation of ______-_________ _______.
Cyclin-dependent Kinase.
39
What are check points?
Delays the cycle to allow for completion of each phase before moving on to the next.
40
What are the 3 chechpoints?
1) DNA damage (G1/S) checkpoint: Is DNA okay for replication? 2) DNA replication (G2/M) checkpoint: is DNA fully replicated before mitosis? 3) Mitotic spindle (M) checkpoint: ARE CHROMOSOMES ALIGNED PROPERLEY IN THE METAPHASE?
41
What is cancer?
Malignant growth caused by uncontrolled cell division, due to altered expression of multiple genes due to mutations.
42
What is the first type of gene involved in cancer?
1) Oncogene: Positive regulators of the cell cycle (GOF) including cyclin D/E (gene amplification) and cdk4 allelles (insensitive to inhibition).
43
What is the second type of gene involved in cancer?
2) Tumor repressor gene: negative regulators of the cell cycle (LOF) including checkpoint genes p53 and RB.
44
Each cancer is caused by ____________ gene mutations, hard to find a ________ cure.
Different Universal
45
Homologous chromosomes:
Parental pair of DNA molecules, where the number and order of genes are the same between homologous chromosomes, but alleles could be different.
46
What is the difference between 2n and n?
2n is the diploid number of DNA molecules (Zygotes). n is the haploid number of DNA molecules (Gametes).
47
What are the five stages of mitosis?
1) Prophase 2) Prometaphase 3) Metaphase 4) Anaphase 5) Telephase
48
Prophase(2n):
4 chromosomes, 2 chromatids. Chromosomes have condensed and become visible, centrosomes move apart and form mitotic spindles, and the nuclear envelope breaks down.
49
Prometaphase(2n):
4 chromosomes, 2 chromatids. Centrosomes reach opposite poles of the cell, sister chromatids are connceted to microtubules at opposite poles, and the chromosomes start migrating towards the equator.
50
What sis the difference between non kinetichore microtubules and kinetichore (spindle) microtubules?
Non-K= attach to each other. K= attach to kinetichore proteins at the centromere.
51
Metaphase(2n):
4 chromosomes, 2 chromatids. DNA molecules are alinged at the equator, sister chromatids are attached at opposite poles.
52
Anaphase(4n-tetraploid):
8 chromosomes, 1 chromatid. Sister chromatids separate, are now independent DNA molecules, kinetichore molecules depolymerize and non-kinetichore molecules lengthen.
53
Telephase(4n):
8 chromosomes, 1 chromatid. Chromosomes cluster at opposite poles+ decondense, nuclear envelope reforms, and cytokenisis begins by furrowing. Goes to G1(2n) where we have two daughter cells that are genetic duplicates of the parent cell.
54
Describe the 5 steps of binary fission (cell cycle in prokaryotes):
1) replication begins at ori. 2) Bacterial chromosome (template + daughter) is attached to the inner membrane. 3) Cell elongates + bacterial chromosomes separate. 4) Inward growth of plasma membrane + partition assembly of new cell wall, dividing relocated DNA. 5) Produces 2 daughter cells.
55
Our germ cells contain __ chromosomes and __ homologous pars.
46 23
56
What are the two stages of meiosis 1?
Prophase and reductional division.
57
Prophase 1(meiosis):
Similar to that of prophase in mitosis except homologous chromosomes synapse to form tetrads. Non-sister chromatids of homologous chromosomes are attached by a protein structure called the synaptonemal complex. Homologus recombination occurs.
58
What is homologous recombination?
Homologous chromosomes exchange pieces of non sister chromatids are exchanged by breakage and reunion (crossing over).
59
Reductional division (meiosis):
During metaphase 1, homologous chromosomes are alinged at the equator facing opposite poles.
60
Genetic diversity in gametes is ____________ due to ________ ___________.
Increased Random assortment
61
What is the chromosome number after meiosis 1?
Haploid, but there are 2 chromatids per chromosome. Sister chromatids are not seperated and no longer identical.
62
Meiosis 2:
No DNA replication happens between meiosis 1/2. Process is otherwise similair.
63
At the end of meiosis 2 what is the number of chromosomes and gametes?
4 gametes, haploid number of chromosomes, 1 chromatid that are not identical due to crossing over and random assignment.
64
What is a vaso-oclusive crisis?
When blood flow is restricted to the organs and causes organ damage.
65
What is CRISPR-cas9?
Gene editing tool, that uses a nuclease(protein that cuts DNA) and a 20nt guide RNA to target specific sites in the genome.
66
What is a sgRNA?
Single guide RNA.
67
What are the first two steps of CRISPR?
1) Engineer a sgRNA with a sequence to a complementary to the target gene. 2) Cas 9 introduces a double stranded break in the DNA targeted by the sgRNA.
68
After the first two steps of CRISPR are completed what are the two possible outcomes?
1) A non homologous end joining to repair a break, causes indels (insertions or deletions). Usually inactivates the gene. 2) Homology-directed repair to swap in the desired sequence.
69
How is CRISPR-cas9 used to cure sickle cell anemia?
KFL1 is a transcription factor that activates expression of Bhb and activates the expression of BC11A, which represses expression of gamma hb.
70
What are enhancers?
Noncoding DNA sequence that binds proteins called transcription factors and activates transcription of a specific nearby gene in cis (on the same chromosome).
71
What is the first/less common method of using cas9 to cure sickle cell anemia?
Fix, crispr and DNA template fix the mutation in the adult hemoglobin gene.
72
What is the second/more common method of using cas9 to cure sickle cell anemia?
Turn off a gene encoding for a repressor of fetal hemoglobin genes. Indels created by cas9 cleavage and NHEJ destroys the GATA-binding site, preventing transcription of the NCL11A gene.
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