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Biochem > Genetics Exam 2 > Flashcards

Genetics Exam 2 Flashcards

(65 cards)

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1
Q

How do genes far apart segregate?

A

Independently

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2
Q

How do genes that are linked segregate?

A

With a frequency dependent on the distance from each other

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3
Q

A two-strand double crossover between two linked genes produces?

A

Non-recombinant gametes

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4
Q

Three types of crossovers can occur over three linked loci.

A

Single -> A and B: Swap of B and C
Single -> B and C: Swap of C
Double -> Swap of B

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5
Q

Study

A

Slide 19 Lecture 6

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6
Q

Three methods of mapping genes on chromosomes

A

Deletion mapping
Somatic cell hybridization
In situ hybridization

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7
Q

Deletion mapping

A

A part of the chromosome is deleted and a homozygous cross occurs. If the chromosome displays the recessive gene you know the gene of interest is in the deletion region.

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8
Q

Somatic-cell hybridization

A

Somatic cell hybridization is when two organisms cells are fused together and the hybrid cells are analyzed for certain gene products.

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9
Q

In situ hybridization

A

Attaches probes on sequences to be analyzed. For example fluorescence.

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10
Q

Aneuploidy

A

One set of chromosomes could have more than 2. For example 2n + 1 = 7

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11
Q

Polyploidy

A

All sets of chromosomes have more than 2. For example 3n = 9

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12
Q

Duplication

A

Genes are duplicated -> Looping out is a characteristic in heterozygotes
Can cause unbalanced gene dosage which leads to abnormalities.

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13
Q

Deletion

A

Removal of genes -> Looping out is a characteristic in heterozygotes
Pseudodominance can occur because recessive alleles are expressed
Haploinsufficient can occur when the deleted copy results in a low gene dosage that has a small effect on the wild-type phenomenon.

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14
Q

Inversion

A

Inverts the sequence of the gene on a chromosome -> They can interrupt individual genes, destroying expression. Genes moved around may experience different expressions due to positional effects. Heterozygous inversions lead to decreased crossing over in the inverted region. When crossed over it can cause non-viable gametes.

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15
Q

Translocation

A

Swaps gene sequences from chromosomes -> Has the same effects as inversion

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16
Q

Robertson Translocation

A

A translocation that combines two giant chunks of chromosomes. An example is chromosome 2 on a human.

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17
Q

Three types of segregation

A
  1. Alternate -> Viable
  2. Adjacent 1 -> Non-viable
  3. Adjacent 2 -> Non-viable
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18
Q

Fragile sites

A

Chromosomal regions that are susceptible to breakage under certain conditions.

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19
Q

Causes of Aneuploidy

A

-Loss of centromere
-Small chromosomes -> Robertson Translocation
-Non disjunction either in Meiosis I or II
-Non disjunction in Mitosis

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20
Q

Types of Aneuploidy

A

Nullisomy - Loss of both chromosomes of a pair
Monosomy - Loss of one chromosome
Trisomy - Gain of an extra chromosome
Tetrasomy - Gain of two extra homologous chromosomes

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21
Q

Aneuploidy in Humans

A

Usually lethal, but can lead to individuals with down syndrome

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22
Q

Causes of polyploidy

A

-Non disjunction either in Meiosis I or II
-Non disjunction in Mitosis

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23
Q

Who discovered DNA was a polymer of nucleotides

A

Phoebus Aaron Levene

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24
Q

Who discovered nitrogenous bases were associated with DNA

A

Albrecht Kossel

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25
Who disproved tetra-nucleotide theory
Erwin Chargaff 1948
26
Who first demonstrated bacteria transformation?
Fred Griffith -> 1928, however could not explain it.
27
Who discovered how transformation actually works?
Avery, Macleod, and McCarty, discovered that DNase was preventing the bacteria from transforming their genetic information.
28
What is T2
A bacteriophage
29
Describe the life cycle of a bacteriophage
1. Phage attaches to a cell and injects its chromosome into the host 2. The host chromosome is broken apart and integrated into the host chromosome 3. More phages are produced, host cell is lysed and killed.
30
Hershey Chase Experiment 1952?
Discovered that DNA is the genetic material in phages.
31
Heinz Fraenkel-Conrat and Singer demonstrated?
That RNA carries the genetic material in TMV (Tobacco Mosaic Virus)
32
Who started studying DNA structure via diffraction?
William Ashbury 1947
33
Primary DNA structure
String of nucleotides joined together by phosphodiester linkages
34
Secondary DNA structure
Three dimensional structure that was discovered by Watson and Crick
35
Tertiary Structure
The complex packaging of double helix into chromosomes
36
Three different forms of DNA?
1. A form 2. B form 3. Z form
37
How is the primary structure in DNA modified?
Through methylation
38
How does DNA condense in tertiary form?
By supercoiling
39
Differentiate histone, nucleosome, and chromatin
1. Histone is the protein DNA is wrapped around 2. Nucleosome is made up of eight histones wrapped together via DNA 3. Chromatin is the description of the "string and beads" that form tertiary structure.
40
What is histone H1?
Acts like a clamp to stabilize DNA around the nucleosome core.
41
30-nm Chromatin
Adjacent nucleosomes packing together
42
Types of chromatin
Euchromatin -> Less condensed, found on chromosomes, contains most genes, often transcribed. Heterochromatin -> More condensed, found at centromeres, and telomeres, mostly made of repeated sequences, contains few genes, crossing over is uncommon.
43
Chromosomal puff
Indicator of where transcription is actively happening
44
Histone tails and their involvement in transcription
When they are positively charged they are tightly bound to the DNA inhibiting transcription factors. Acetylation weakens the interaction causing the DNA to be more accessible.
45
Centromeres
Constricted region to which spindle fibers attach during mitosis and meiosis.
46
Telomeres
Sequences at the end of chromosomes, highly repeated sequences that interact with proteins.
47
What are required to make Artificial Chromosomes in eukaryotes
1. Telomeric sequences specific to the organism 2. Centromeric sequences specific to the organism 3. One or more origins of replication
48
Transposable elements
1. Ubiquitous among forms of life 2. Comprise of a high percentage of the genome
49
Two major classes of transposons
-Dna only -Retrotransposons (uses RNA intermediate)
50
What ways can transposons drive chromosomal rearrangement?
Deletion Duplication Inversion
51
Transposable element can cause flanking direct repeats?
True
52
Transformation
Uptake of DNA from the environment
53
Transduction
Phage mediated transfer of DNA
54
Conjugation
Transfer via cell to cell contact
55
The F factor
Integrated in a bacterial chromosome in an HFr cell
56
R plasmid
Conjugative plasmids that carry antibiotic resistance genes
57
Bacteriophages can have two alternative life cylces
Lytic Lysogenic
58
Primary Down Syndrome
Three copies of chromosome 21
59
Familial Down Syndrome
Translocated chromosome from 21 to 15
60
Specialized transduction
Is specific to a certain sequence of the chromosome
61
Types of Inversion
Paracentric -> Specific to a certain spot Pericentric -> Include the centromere
62
F+
Present as separate circular DNA
63
F-
Absent
64
Hfr
Present, integrated into the bacterial chromosome
65
F'
Present as a separate circular DNA, carrying some bacterial genes

Biochem (8 decks)

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