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Genetics > Lecture 4 > Flashcards

Lecture 4 Flashcards

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Biology 101 flashcards
1
Q

define gene

A

unit of heredity that comprises a stretch of DNA that codes for a type of protein- some visible, some not visible

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2
Q

define autosomes

A

The first 22 pairs of chromosomes other than the sex chromosome

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3
Q

What is the 23rd pair of chromosomes called?

A

sex chromosomes

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4
Q

How is a karyotype produced?

A

produced by staining and photographing the chromosomes as they divide- individual chromosomes are then cut out and paired with their homologous pair

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5
Q

how do biologists identify the homologous pairs?

A

based on size, shape, position of centromere and stained bands

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6
Q

define loci

A

location of the allele on the chromosome

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7
Q

how many chromosomes do sex cells such as sperm or eggs have?

A

23 haploid chromosomes

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8
Q

define gene mapping

A

the process of determining the locus for a particular biological trait

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9
Q

locus for a gene written as 11q1.4 means what?

A

q arm of 11th chromosome, band 1, sub band 4

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10
Q

the tallest chromosome (#1) has how many genes?

A

4200 genes

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11
Q

Shortest y chromosome has how many chromosomes?

A

450 genes

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12
Q

What are genetic disorders caused by?

A

mutation of genes

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13
Q

Disorders caused by mutation of genes is called what?

A

muted/defective/disease genes

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14
Q

define mutation

A

a random, undirected, heritable variation caused by alteration in the gene nucleotide sequence at some point of DNA of the cell

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15
Q

How can mutation happen?

A

addition, deletion, substitution

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16
Q

What happens in substitution?

A

One base pair is inserted in place of another- takes place at time of DNA replication due to error of DNA polymerase

17
Q

Missense mutation

A

When the substitution results in a codon that simply causes a different amino acid production

18
Q

nonsense mutation

A

If it stops protein synthesis by becoming a stop codon sooner than predicted

19
Q

Frame shift mutation

A

Occurs when one or two base pairs inserted/deleted- wrong aa are produced down stream

20
Q

Point mutation

A

any insertion/deletion entirely

21
Q

Chromosomal abberations

A

Any change in the normal structure of a chromosome-Whole chromosome extra, missing or both

22
Q

What happens in a tri-nucleotide repeat disorders

A

gene is extended in length

23
Q

How can mutations be induced?

A

by UV rays, alkylating agents, 5 Bromouracid, Acridin dyes

24
Q

How many amino acids are there?

A

20 aa

25
Q

What pedigree pattern is shown from autosomal dominant disease?

A

vertical pattern of inheritance

26
Q

Complete Penetrance

A

Means that all individuals who have defective allele show clinical symptoms of the disease

27
Q

Reduced Penetrance

A

(incomplete penetrance)- when some individuals fail to express the trait, even though they carry the defective allele

28
Q

What pedigree pattern is shown from autosomal recessive disease?

A

horizontal pedigree pattern

29
Q

examples of autosomal recessive disorders

A

cystic fibrosis, sicke cell, tay-sachs, phenylketonuria and galactosemia

30
Q

Define incomplete dominance

A

alleles are neither dominant nor recessive- when two different alleles are combined, the resulting expression is somewhere between the two

31
Q

example of incomplete dominance

A

snapdragon flower color- crossing homozygous red with homozygous white snapdragon plants produces heterozygous offspring that have pink flowers

32
Q

example of incomplete dominance in humans

A

inheriting a gene for curly hair from one parent and a gene for straight hair from the other will give wavy hair

33
Q

Define single dominance

A

either we have the allele or we don’t

34
Q

examples of single dominance

A

ear attachment, tongue rolling, PTC tasting

35
Q

define co-dominance

A

The gene present in both alleles expresses the trait in phenotype

36
Q

Example of human co-dominance disorder

A

ABO blood type (AB blood group is A and B blood)

37
Q

Define polygenic inheritance

A

several genes for one trait - multiple alleles for one trait

38
Q

What blood type has an absence of antigens?

A

Blood type O

39
Q

define multiple alleles

A

having more than two different alleles for the gene

Genetics (12 decks)

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