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Heredity Flashcards

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Biology 101 flashcards
1
Q

Homologous pairs?

A
  • 2 different copies of the same chromosome in a diploid organism
  • 1 from each parent
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2
Q

Penetrance?

A

Proportion of individuals who have the phenotype associated with a specific allele

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3
Q

Incomplete dominance?

A

When one allele is not completely expressed over its paired allele. (R x W= Pink)

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4
Q

Codominance

A

when the heterozygous genotype expresses both alleles. (Ex. red x white = red + white spots).

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5
Q

Pleiotropy

A

when one gene is responsible for many traits
- single gene has multiple phenotypic outcomes

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6
Q

Polygenic inheritance

A

when many genes are responsible for one trait
- multiple genotypes are affecting one phenotype

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7
Q

Haploinsufficiency

A

1 copy of the gene is lost/ nonfunct. and the expression of the remaining copy is not sufficient enough to result in a normal phenotype

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8
Q

What organelle contains DNA that only comes from our maternal side?

A

mitochondria

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9
Q

Proto-oncogenes

A

are genes that can become oncogenes (cancer-causing genes) due to gain-of-function mutations. Cancerous growth occurs as a result
- Normally involved in cell cycle control.
- Follow 1 hit hypothesis

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10
Q

Gain-of-function mutations?

A

Causes too much protein to be made or production of an over-active protein

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11
Q

One hit hypothesis?

A

A gain-of-function mutation in one copy of the gene turns it into an oncogene.

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12
Q

Tumor-suppressor genes?

A
  • Genes that become cancerous as a result of loss-of-function mutations
  • Normally needed to suppress cancerous growth.
  • follow the two hit hypothesis
  • Are haplosufficient
  • Have null alleles when they become cancer-causing.
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13
Q

Two hit hypothesis?

A

A loss-of-function mutation in both copies of the gene are needed to make it cause cancer.

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14
Q

Null alleles?

A

From mutations that cause the alleles to lack normal function. Tumor-suppressor genes have null alleles when they become cancer-causing.

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15
Q

What are the 3 important tumor-suppressing genes?

A

p53
p21
RB gene

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16
Q

p53 is what?

A

-Tumor-suppressor gene
- Guardian of the cell
- Upregulated to prevent cells from becoming cancerous

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17
Q

p21 is what?

A
  • Tumor-suppressor gene
  • Inhibits phosphorylation activity in order to decrease rampant cell division.
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18
Q

Retinoblastoma gene (RB) is what?

A
  • Tumor-suppressor gene
  • Codes for a retinoblastoma protein
  • Prevents excessive cell growth during interphase.
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19
Q

Nondisjunction is what?
What are the types of this?

A
  • Improper segregation of chromosome pairs during anaphase
  • Produces daughter cells with an incorrect # of chromosomes
  • Two types: one occurs in Meiosis 1, another occurs in Meiosis 2
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20
Q

Single nondisjunction of homologous chromosomes during meiosis I #’s

A

2n+1, 2n+1, 2n-1, 2n-1

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21
Q

Single nondisjunction of homologous chromosomes during meiosis 2 #’s

A

2n, 2n, 2n+1, 2n-1
- only one side is affected

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22
Q

Single nondisjunction of sister chromatids during mitosis #’s

A

2n+1, 2n-1

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23
Q

Aneuploidy

A

Abnormal # of chromosomes in the daughter cells

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24
Q

Trisomy

A

3 chromosome copies (or 1 extra copy)

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25
Q

Monosomy

A

1 chromosome copies (1 missing copy)

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26
Q

Disomy

A

Refers to a normal diploid cell.

27
Q

Down syndrome

A

Trisomy of chromosome #21 (each diploid cell has 47 chromosomes total).

28
Q

Turner syndrome

A

Monosomy of X chromosome in females (each diploid cell has 45 chromosomes total).

29
Q

Klinefelter’s syndrome

A

Trisomy of X in males
Giving them XXY (each diploid cell has 47 chromosomes total)

30
Q

Trisomy X

A

Trisomy of X in females
Giving them XXX (each diploid cell has 47 chromosomes total)

31
Q

True-breeding?

A
  • Organisms are homozygous for all the traits of interest
32
Q

Single allele crosses ratios
Homozygous x Homozygous

A

1/1 AA or 1/1 Aa or 1/1 aa

33
Q

Single allele crosses ratios
Homozygous x Heterozygous

A

1/2 AA OR 1/2 aa
AND 1/2 Aa

ex. 1/2 aa and 1/2 Aa

34
Q

Single allele crosses ratios
Heterozygous x Heterozygous

A

1/4 AA, 1/2 Aa, 1/4 aa

35
Q

How do you understand/figure out multiple allele crosses?

A

You multiply the single allele cross ratios
- MULTIPLY the denominators!

36
Q

Pedigree Charts
What is the symbol for females?

A

Circles

37
Q

Pedigree Charts
What is the symbol for males?

A

Squares

38
Q

Pedigree Charts
What is the symbol for affected individuals?

A

A shaded circle/square is affected, not affected is not shaded

39
Q

Where is genetic material at points exchanged during crossing over?

A

Chiasmas

40
Q

What does autosomal dominant mean?

A

Non-sex gene, only 1 mutant gene required to cause disorder
equal frequency in both sexes!

41
Q

What does autosomal recessive mean?

A

Non-sex gene, 2 mutant genes required to cause disorder
skipping of generations!

42
Q

Linked genes

A

Different genes in close physical proximity on the same chromosome

43
Q

Epistasis

A

Occurs when one gene affects the expression of a second gene

44
Q

_____ changes can cause _____ twins to have different susceptibilities to the same disease.

A

Epigenetic, monozygotic

45
Q

Recombination frequencies of _______ mean that the two genes are _______.

A

less than 50%, linked

46
Q

Haplotype

A

Group of genes that are usually inherited together because they are located in close proximity to each other

47
Q

What are the three types of sex-linked traits

A

X-linked dominant
X-linked recessive
Y-linked

48
Q

X-linked dominant

A

sex gene, only 1 mutant gene required
dad affected, ALL daughters are affected

Dominant inheritance on the X chromosome. Any offspring (male or female) that receive the affected allele will end up with the disorder.

49
Q

X-linked recessive

A

sex gene, 2 mutant genes required
Females: 2 affected alleles are needed to cause the disorder
Males: only 1 affected allele is needed to cause the disorder
more affected males!
Recessive inheritance on the X chromosome

50
Q

Y-linked

A

sex gene
ALWAYS expressed, dominant or recessive because males only have one Y chromosome.
ONLY be passed from father to son (very rare)

51
Q

How many X chromosomes do women have?

A

2 X chromosomes

52
Q

Examples of X-linked recessive conditions.

A

Hemophilia and Color-blindness

53
Q

Genomic imprinting

A

Genes that are expressed depending on parental origin

54
Q

X-inactivation

A

Process by which one of a female’s X chromosomes is inactivated, forming a Barr body and preventing excess transcription
Female carrier can become affected

55
Q

Epigenetics

A

Does not involve modifying the genetic code, but instead the regulation of when genes are expressed.

56
Q

Examples of epigenetics

A

DNA methylation
Histone acetylation
Histone de-acetylation
Histone methylation

57
Q

DNA methylation

A

Decreases gene expression by the suppression of genes. This is done through the addition of methyl groups, recruiting methyl-binding proteins (MBDs) and preventing transcription factors from binding.

58
Q

Histone acetylation

A

causes gene activation and formation of euchromatin (easily accessible DNA).

59
Q

Histone de-acetylation

A

causes gene suppression (think ‘de-activation’) and formation of heterochromatin (hard to access DNA).

60
Q

Histone methylation

A

can upregulate/downregulate gene expression

61
Q

Euchromatin

A

easily accessible DNA

62
Q

Heterochromatin

A

hard to access DNA

63
Q

Allele

A

one variation of a gene

DAT BIO (22 decks)

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