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Genetics Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Why is an organism’s collection of genes like a deck of cards?

A

Genes can be snuffed and passed, but aren’t “mixed” together

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2
Q

What did Mendel document in his garden?

A

A particulate mechanism for inheritance

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3
Q

A “character” is?

A

a heritable feature that varies among individuals (flower color)

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4
Q

A “trait” is?

A

Every variant for a character (purple flower)

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5
Q

Why were peas a good model organism

A

They are self-fertilizing so Mendle could assure parentage.

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6
Q

“True Breeding” means?

A

Over many generations of self-pollinating the plants produced the same variety as the parent plant

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7
Q

What happens if one crosses two different “purebred” plants

A

You would be conducting hybridization and would end up with p and F1 generation

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8
Q

Describe Mendel’s monohybrid pea plant experiment

A

Mendel crossed 2 pure-breeding varieties of pea plants. He transferred pollen from the white flower to the purple. The F1 generation produced all purple flowers but the F2 generation produced a 3/1 purple-to-white ratio. He discovered recessive and dominate genes.

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9
Q

What do we call Mendel’s “factors” now

A

We call them genes now, but Mendel used heritable factors because he didn’t understand or know about Chromosomes or Genes

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10
Q

What are Mendel’s four related concepts that make up his particulate model of inheritance

A
  1. Alternate versions of genes account for variations of inherited characters. The variation of DNA affects the information it codes for
  2. For each character, an organism inherits two versions of a gene, one from each parent. Each somatic cell has 2 sets of chromosomes, one from each parent
  3. If the two alleles at the locus differ, then one, the dominate allele determines organism appearance, and two the recessive allele has no impart
  4. Law of segregation- two alleles for a charitable character segregate during gamete formation and end up with different gametes
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11
Q

Homozygous

A

An organism that has a pair of identical genes coding for a character is said to be homozygous

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12
Q

Heterozygous

A

An organism that has two different alleles to code for a character

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13
Q

Genotype

A

The genetic make up of an organism

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14
Q

Phenotype

A

The physiological and physical traits of an organism (observable)

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15
Q

Law of independent assortment

A
  • 2 Characteristics
  • Second law of inheritance
  • Law of independent assortment
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16
Q

What is the Dihybrid cross?

A

The dihybrid cross is when you cross 2 things with 2 different characteristics instead of just one. The Gametes could have any possible combination of the 2 characteristics. This is known as the law of independent assortment (genes are on different chromosomes)

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17
Q

What is the multiplication rule?

A

The way to determine the probability of one event and the other(s) occurring is to multiply the probabilities

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18
Q

What is the addition rule?

A

The probability that two or more mutually exclusive events will occur is calculated by adding their individual probability

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19
Q

Why did Mendel count so many offspring from his crosses

A

He understood the statistical nature of inheritance and also the rules of chance.

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20
Q

What is the Incomplete Dominance Inheritance pattern

A

Complete dominance means one allele pair completely took over in the case of phenotype (genotypes become indistinguishable) Incomplete dominance is when 2 genes are crossed and the F1 Generation has a “medium” level of the gene

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21
Q

What happens in a codominance inheritance pattern

A

When two alleles have distinguishabe effects on the phenotype in separate ways. This looks like 2 variables of a gene both being present.

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22
Q

How many alleles are there for blood type

A

3

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23
Q

What is pleiotropy

A

The ability of one gene to have multiple effects

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24
Q

What is epistasis

A

A type of gene interaction in which the phenotypic expression of one gene alters that of another independently inherited gene

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25
Q

Quantitative characters generally indicate

A

A heritable feature that varies continuously over a range, rather than in an either-or fashion

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26
Q

How many genes effect skin coloration

A

378

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27
Q

Some Characters are multifactorial, which means that

A

a phenotypic character is influenced by multiple genes and environmental factors

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28
Q

What is a pedigree

A

A pedigree follows the occurrence of a trait across multiple generations through symbols denoting male/female and generational mating. Helps find genetic and inheritance patterns

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29
Q

Tay Sachs

A

Tay-Sachs is more prominent among Ashkenazic Jews. Occurs from genetic history in less technological times. When inbreeding occurs the chance of a recessive trait occurring increases. 1/3600 births 100x more than non jews

30
Q

Cystic Fibrosis

A

1/2500 people of European descent have cystic fibrosis, 1/25 people is a carrier, and the normal gene codes for the transport of Chloride ions. This can cause death by 5

31
Q

Sickle Cell Anemia

A

Prevalent among African Americans occurring in 1/365 births, at an organismal level the normal allele is completely dominant. At a molecular level, they are codominant. Heterozygotes are healthy but typically suffer some symptoms. 1/10 have a single-cell trait

32
Q

Huntington’s

A

A degenerative disease 1/10000 people. Only lethal when it is homozygotes. This disease is irreversible and present at around 35-40 years. A child born to a parent of Huntington’s has a 50% chance of getting it.

33
Q

Achondroplasia

A

A form of Dwarfism that occurs in 1/25000 people. It is a dominant gene so the 99.99% of people that don’t have achondroplasia are recessive. It is relatively harmless

34
Q

What is a Mendel Factor

A

Segments of DNA that are located along chromosomes

35
Q

What are 3 parallels between Mendel Factors and Chromosomes?

A

1) Chromosomes and genes are both present in pairs in diploid cells
2) Homologous chromosomes separate and alleles segregate in meiosis
3) After meiosis fertilization restores the paired condition

36
Q

What is the phenotypic ratio of a dihybrid cross

A

9:3:3:1

37
Q

What makes fruit flies a good model organism

A

They are prolific breeders so one mate will produce hundreds of offspring

38
Q

What does “wild type” mean?

A

The phenotype most commonly observed in natural populations

39
Q

When Morgan mated his mutant white-eyed fly to the red, the white-eyed recessive trait showed up only in males, why did that happen?

A

The flies’ eye color was linked to sex. It suggested that the genes involved in the mutation were only on the x chromosome

40
Q

What is the chromosomal theory of inheritance

A

A specific gene is carried on a specific chromosome

41
Q

Which of Mendels laws describes the inheritance of alleles for a single character

A

Law of segregation

42
Q

Which of Mendel’s laws describes the inheritance of alleles for two characters in a dihybrid cross

A

law of independent assortment

43
Q

When purebred white-eyed flies mate with homozygous red-eyed flies, all the baby flies have red eyes. Which of Mendel’s laws is that?

A

Law of dominance

44
Q

What is the difference in x and y sex chromosomes

A

the x chromosome is much larger than the y

45
Q

Is there any part of the two sex chromosomes that are homologous?

A

Short regions at the ends of the Y chromosome are homologous with segments of the x

46
Q

What causes the development of the testes in the embryo, what happens if it isn’t present

A

A gene named SRY (sex-determining region) is responsible for the development of testes. If SRY is absent then ovaries will form

47
Q

How many genes are on the Y Chromosome

A

78

48
Q

How many genes are on the x Chromosome

A

1100

49
Q

What is the difference between sex-linked and X linked

A

sex-linked gene can be on either chromosome, x-linked is a gene specifically on the x chromosome, show a specific pattern of inheritance

50
Q

Who do fathers pass their x’s on to

A

daughters

51
Q

Who do mothers pass theirs x’s on to

A

all children

52
Q

What are 3 x-linked traits

A

Colorblindness, Duchenne muscular dystrophy, Hemophilia

53
Q

What happens to the extra X that XX people get

A

It becomes deactivated and only reactivates in the ovaries for meiosis

54
Q

How many genes are on the usual chromosome

A

hundreds of thousands

55
Q

Why are linked genes inherited together

A

If genes are near to each other on a chromosome they can be linked, this was discovered in Mogan Drosophilia experiments

56
Q

What is genetic recombination

A

The production of offspring with combinations of traits not found in either parent

57
Q

Why do meiosis and random fertilization generate genetic variation

A

During those processes, independent assortment and crossing-over happen which increases the variation

58
Q

What is the source of all new alleles?

A

Random mutations are the source of all new alleles, this means new phenotypic traits

59
Q

What do meiosis and random fertilization generate in genetic variation?

A

During those processes, independent assortment and crossing happen which increases the variation

60
Q

Aneuploidy

A

a chromosome aberration where one or more chromosomes has an extra copy

61
Q

Monosomic

A

A diploid chromosome that only has one copy instead of the normal two

62
Q

Trisomic

A

a trisomic is a diploid cell with 3 copies of a chromosome instead of two. This is the specific thing happening when Down Syndrome occurs

63
Q

Polyploidy

A

An alteration where the organism possesses more than two complete chromosome sets. (accidental cell division)

64
Q

What two things can cause a breakage of chromosomes

A

Errors in meiosis or damaging agents (radiation) can cause a breakage of chromosomes

65
Q

Deletion

A

Occurs when a chromosomal fragment is lost. The affected chromosome is then missing certain genes

66
Q

Duplication

A

Due to fusion with a fragment from a homologous chromosome such that a portion of a chromosome is duplicated

67
Q

Inversion

A

Reattachment of a chromosomal fragment in a reverse orientation from the chromosome it originated

68
Q

Translocation

A

Attachment of a chromosome to one non homologous

69
Q

What happens becuase of uneven cross over

A

One chromosome would have a deletion and one would have a duplication

70
Q

Why is it harmful if a reciprocal translocation was to happen?

A

A lot of gene phenotypes can be impacted bu the genes around them, this means even though the balance is there the effects can be devastating

71
Q

Why don’t 20-40% of people have aneuploidies

A

A lot of aneuploidies are so disastrous that they lead to a spontaneous abortion long before birth

Biology (3 decks)

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