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Cell biology > Genetic variations > Flashcards

Genetic variations Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is a polymorphism?

A

A DNA variant with a frequency of more than 1% in the population (has to have 2 or more alleles)

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2
Q

What is the most common type of polymorphism?

A

SNP - single nucleotide polymorphism

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3
Q

How are SNPs distributed in the DNA and how are they inherited?

A

Distributed evenly, approximately every 100 bp. They are inherited in haplotype blocks or linkage groups - because of the limited opportunity of crossing over in meiosis.

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4
Q

Name the 4 types of extragenic DNA sequences

A
  1. Unique DNA (single copy)
  2. Low copy repetitive DNA
  3. Moderatley repetitive DNA
  4. Highly repetitive DNA
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5
Q

Which type of extragenic DNA sequence is highly conserved through evolution?

A

Unique DNA - often has a function in gene regulation.

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6
Q

Where are low copy repetitive DNA sequences found?

A

Close to centrosomes

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7
Q

What are highly repitive DNA sequences derived from?

A

Mobile DNA elements

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8
Q

Name a type of highly repetitive DNA in humans, what are they?

A

Transposons - DNA sequences that can move in the genome.
Retrotransposons - type of transposon. Sequence is copied by reverse transcriptase and inserted back into the DNA
Transposons - sequence of DNA that moves using cut and paste

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9
Q

What is the importance of transposons?

A

Creates novel genes, allows exon shuffling.

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10
Q

What is penetrance?

A

The proportion of a population with a genotype that shows the associated phenotype

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11
Q

What is expressivity?

A

Qualitative or quantitative variations in the phenotypes among individuals with a specific genotype.

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12
Q

What effects can DNA mutations have on gene expression?

A

Effects the regulatory region - change the expressivity of the gene

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13
Q

What effect can DNA mutations have on protein function?

A

Loss of function, gain of function, dominant-negative (interacts with wild type gene and loses function)

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14
Q

Complex diseases are all polygenic. They can be additive or non-additive, what does this mean?

A

Additive - equal contribution of all gene loci.

Non-additive - unequal contribution of all gene loci

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15
Q

Is there a familial tendency in complex diseases?

A

Yes with close relations but still a lot lower than expected.

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16
Q

What causes numerical abnormalities?

A

Non-dysjunction during meiosis or mitosis.

17
Q

What is aneuploidy?

A

Loss or gain of 1 or more chromosomes.
Monosomy - loss of 1
Triploidy - gain 1

18
Q

What is polyploidy?

A

Gain of 1 or more complete chromosome sets

19
Q

Why are chromosomal abnormalities not common in the population?

A

Often cause embryonic fatality

20
Q

What can cause structural changes?

A

Chromosomal breakage and abnormal reunion or unequal crossing over during recombination.

21
Q

What is translation and what are the different types?

A

Transfer from 1 chromosome to another. Caused by chromosomal breakage and abnormal reunion.
Reciprocal - 2 chromosomes exchange segments.
Robertsonian- breakpoint is near the centromere of an acocentric chromosome.

22
Q

What is inversion and what are the different types?

A

Chromosome segment is reversed.
Pericentric - involves the centromere
Paracentric - only involves 1 arm

23
Q

What is insertion and deletion?

A

Caused by unequal crossing over during recombination. part of chromosome is inserted into another or lost.

24
Q

What is a ring chromosome?

A

Broken chromosome forms a ring

25
Q

What is an isochromosome?

A

Loss of 1 arm and duplication of the other.

26
Q

What is the difference between a transition nucleotide substitution and transversion?

A

Transition is replacing a pyrimidine for a pyrimidine or purine for purine.
Transversion is replacing purine for pyrimidine or reverse.

27
Q

What is a silent mutation

A

Codes for the same amino acid

28
Q

What is a missense mutation?

A

codes for a different AA

29
Q

What is a nonsense mutation?

A

Codes for a stop codon

30
Q

What is a splice site mutation?

A

causes exon skipping or intron retention

31
Q

What is a regulatory mutation?

A

causes changes to expression levels.

Cell biology (13 decks)

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