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Genetics > Week 1 > Flashcards

Week 1 Flashcards

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Biology 101 flashcards
1
Q

What is cross-fertilization

A

crossed tall and dwarf pea plants to investigate how height was inherited

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2
Q

What is the latent factor?

A

The recessive gene

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3
Q

What is the expressed factor?

A

the dominant gene

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4
Q

What is a dominant gene?

A

A term applied to an allele that is manifested to the exclusion of a different allele in a heterozygote

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5
Q

What is an allele?

A

One of a pair, or series, of alternative forms of a gene that occur at a given locus in a chromosome.

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6
Q

What is a monohybrid cross?

A

A cross between parents differing in only one trait or in which only one trait is being considered.

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7
Q

What is a gene?

A

A hereditary determinant of a specific biological function

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8
Q

What is a homozygote?

A

An individual in which the two
copies of a gene are the same allele.

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9
Q

What is a heterozygote?

A

An organism with unlike members of any given pair or series of alleles that consequently produces unlike gametes.

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10
Q

What is a genotype?

A

The genetic constitution (gene makeup) of an organism

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11
Q

What is a Phenotype?

A

The observable characteristics of an organism.

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12
Q

What makes up the P generation?

A

The parental generation

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13
Q

What makes up the filial
generation (F1)?

A

the first generation of descent from a
given mating.

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14
Q

What makes up the F2 generation?

A

The second filial generation produced by self-pollinating the F1. The inbred “grandchildren” of a given
mating.

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15
Q

What is the Principle of Dominance?

A

In a heterozygote, one allele may conceal the presence of another. (Dominance)
This principle is a statement about genetic function.
Some alleles evidently control the phenotype even when they are present in a single copy.
The alleles of a gene are either dominant or recessive

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16
Q

What is the Principle of Segregation?

A

In a heterozygote, two different alleles segregate from each other during the formation of gametes.
This principle is a statement about genetic transmission.
An allele is transmitted faithfully to the next generation, even if it was present with a different allele in a heterozygote.
The biological basis for this phenomenon is the pairing and subsequent separation of homologous chromosomes during meiosis.

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17
Q

What is the Principle of Independent Assortment?

A

The alleles of different genes assort independently of each other.
This principle is another rule of genetic transmission, based on the behavior of different pairs of chromosomes during meiosis.
However, not all genes abide by it.

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18
Q

What are Mendels three principles of inheritance?

A
  1. The Principle of Dominance
  2. The Principle of Segregation
  3. The Principle of Independent Assortment
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19
Q

What is the principle of independent assortment also referred to?

A

A dihybrid cross

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20
Q

What is a Dihybrid cross?

A

An individual that is heterozygous for
two pairs of alleles; the progeny of a cross between homozygous parents differing in two respects.

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21
Q

How many phenotypes are there is the F2 generation of a dihybrid cross? What is the usual phenotypic ratio?

A

4
(9:3:3:1)

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22
Q

What do punnett squares display?

A

Initially the genotype and later, the phenotype

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23
Q

What is an intercross?

A

A cross between the F1 hybrids derived from a cross between two parental strains

24
Q

On a pedigree, what is the symbol for:
-Female
-Male
-People who have the trait
-Deceased
-Unidentified gender
-Number of Children
-Carrier

A

Female: Circle
Male: Square
People who have the trait: Red/colour
Deceased: Line through shape
Unidentified gender: diamond
Number of Children: # in circle
Carrier: Half coloured

25
Q

What is included on a pedigree chart?

A
  1. Title
  2. Roman numerals for generations
  3. Arabic numerals for individuals within the generations
26
Q

What is incomplete, or partial dominance?

A

Expression of two alleles in a heterozygote
that allows the heterozygote to be distinguished from either of its homozygous parents. (Pink flower; instead of red (dom) or white (rec))

27
Q

Why does incomplete dominance occur?

A

The most likely explanation is that the intensity of pigmentation in this species depends on the amount of a product specified by the color gene (Dominant gene (W))

28
Q

What is semi-dominance?

A

A term applied to alleles in which the phenotype of a heterozygote is midway between the phenotypes of the corresponding homozygotes

29
Q

What is Co-dominance?

A

Codominance implies that there is an independence of allele function. Neither allele is dominant, or even partially dominant, over the other.
It would therefore be inappropriate to distinguish the alleles by upper- and lowercase letters, as we have in all previous examples

30
Q

How are co-dominant alleles represented?

A

Instead, codominant alleles are represented by superscripts on the symbol for the
gene

31
Q

What is a wildtype? Give an example

A

The customary phenotype or standard for comparison.
Ex. Because most rabbits in wild populations are homozygous for the c+ allele, this allele is called the wild type.
It is customary to represent wild-type alleles by a superscript plus sign after the letter for
the gene.

32
Q

What happens when there are multiple alleles? (use bunnies as an example)

A

The color-determining gene, denoted by the lowercase letter c, has four alleles, three of which are distinguished by a superscript: c (albino), c^h (himalayan), c^ch (chinchilla), and c^+ (wild-type).
In homozygous conditions, each allele has a characteristic effect on the coat color.

33
Q

What are mutants? (use the bunnies as an example)

A

The other alleles of the c gene are mutants; altered forms of the wildtype allele that must have arisen sometime during the evolution of the rabbit. (The himalayan, chinchilla and albino)

34
Q

What happens in an allelic series? (give an example)

A

For example, the four alleles of the c gene in rabbits can be combined with each
other to make six different kinds of heterozygotes
The wild-type allele is completely dominant over all the other alleles in the series; the chinchilla allele is partially dominant over the himalayan and albino alleles, and the himalayan allele is completely dominant over the albino allele. These dominance relations can be summarized as c+ > c ch > c h > c.
The wild-type allele is fully functional in this process, producing colored hairs throughout the body. The chinchilla and himalayan alleles are only partially functional, producing some colored hairs, and the albino allele is not functional at all

35
Q

What is another word for a non-functional allele? Give an example (bunny)

A

Nonfunctional alleles are said to be null or amorphic; they are almost always completely recessive (albino bunny)

36
Q

What is another word for a partially functioning allele?

A

Partially functional alleles are said to be hypomorphic; they are recessive to alleles that are more functional (inbetween colours)

37
Q

What is a fully functioning allele?

A

Usually the wildtype (dominant colour)

38
Q

What type of alleles are recessive mutations?

A

Recessive mutations are therefore typically loss of-function alleles.

39
Q

What is a complementation test?

A

Introduction of two recessive mutations into the same cell to determine whether they are alleles of the same gene, that is, whether they affect the same genetic
function. If the mutations are allelic, the genotype m1 +/+ m2 will exhibit a mutant phenotype, whereas if they are nonallelic, it will exhibit the wild phenotype.

40
Q

What are sterile mutations

A

Mutations that prevent reproduction

41
Q

What are lethal mutations

A

Mutations that interfere with necessary vital functions
Their phenotypic effect is death

42
Q

How are recessive lethal mutations detected

A

By observing unusual segregation ratios in the progeny of heterozygous carriers

43
Q

What type of effect do zygotes with dominant mutations have?

A

phenotypic effects in heterozygotes as well as in homozygotes

44
Q

If you have a pair of alleles, one with a wildtype and one a recessive, what is the phenotype?

A

That of the wildtype

44
Q

If you have a pair of alleles and one is dominant, what is the phenotype?

A

That of the dom. allele (mutant)

45
Q

What is a dominant- negative
mutations

A

a dominant mutation that interferes with the function of the wild-type allele by specifying polypeptides that inhibit, antagonize, or limit the activity of the wild-type polypeptide

46
Q

Why is incomplete penetrance a problem in pedigree analysis

A

because it can lead to the incorrect
assignment of genotypes.

47
Q

What is variable expressivity?

A

When a phenotype is not variable and changes even if it is considered a dom. trait

48
Q

What is the difference between variable expressivity and incomplete penetrance?

A

Incomplete penetrance: does not display in everyone, is a carrier

Variable expressivity: a range of expression of a gene in different ways

49
Q

What is epistasis?

A

When two or more genes influence a trait, an allele of one of them may
have an overriding effect on the phenotype

50
Q

Give 4 examples of epistasis

A

-Fly white mutation epistatic to the cinnabar mutation
-color in the sweet pea flower
-the inheritance of fruit
color in summer squash plants
-colour of labradors

51
Q

Expand on the epistasis of labs

A

gene 1: dominant B- (black), recessive bb (brown)
gene 2: dominant E-(no effect), recessive ee (yellow)

52
Q

Expand on the squash epistasis

A

(ww) and (YY or Yy) generates yellow fruit

wwyy genotype produces green fruit.

53
Q

Expand on epistasis of flowers

A

The dominant allele P must be present to produce purple flowers.
If the plant has (cc), the flowers will be white. Therefore, gene C is epistatic to gene P.

54
Q

Expand on epistasis of fly eyes

A

In a fly with a mutation in the white gene, neither pigment can be produced, and the fly will have white eyes regardless of the genotype at the brown or scarlet loci

55
Q

What is Heterosis

A

The science of making hybrids, removes genetic breeding

Genetics (9 decks)

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