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Lecture 12: Genetics Flashcards

(73 cards)

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1
Q

Which concept was accepted and favoured before the acceptance of Mendels pee research?

A

The concept of blending

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2
Q

Give a summary of Mendel’s research.

A

Mendel selected varieties of peas and studied them for heritable characters and traits.
He looked for characters that had well defined alternative traits that were true-breeding.
Then he looked at the generations of the peas. There was -parental generation (P)
-first filial generation (F1)
-the progeny (F2)

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3
Q

What is a monohybrid cross?

A

It is the experiment that involves one character (ex: seed shape) and their different traits (ex: spherical or wrinkled)

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4
Q

What is the particular theory?

A

It is the units responsible for inheritance that are discrete particles that exist within an organism in pairs and separate during gamete formation.

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5
Q

During the production of gametes, how many pairs of a given character are passed down?

A

One pair

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6
Q

What happens during fertilization?

A

The zygote gets one unit from each parent, restoring the pair.

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7
Q

What are the units of inheritance now called?

A

Genes

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8
Q

What are the different forms of a gene now called?

A

Alleles

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9
Q

What are true breeding individuals that have two copies of the same allele called?

A

Homozygous.

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10
Q

What are the individuals that have two copies of different alleles called?

A

Heterozygous.

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11
Q

What is the actual composition of an organism’s alleles for a gene called?

A

Genotype.

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12
Q

What is the physical appearance of an organism called?

A

Phenotype.

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13
Q

What is Mendel’s first law?

A

The law of segregation: two allies of a gene separate when an individual makes gametes.

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14
Q

Where is the gene found on achromosomal DNA

A

it is found on a portion at a specific site called a locus.

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15
Q

True or false. Each gene code for different functions.

A

False. Each gene code for a particular function.

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16
Q

What method is used to determine possible allelic combinations, resulting from fertilization?

A

Punnett Square.

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17
Q

What is a test cross?

A

It is an individual with a dominant trait with a true breeding recessive that can determine the first individual genotype.

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18
Q

What is the result of a test cross if the unknown is heterozygous?

A

Approximately half of the progeny will have the dominant trait and half will have the recessive trait.

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19
Q

What is the result of the test cross if the unknown is homozygous dominant?

A

All progeny will have the dominant trait.

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20
Q

What is Mendel second law?

A

Law of independent assortment: alleles of different genes assort into gametes independently of each other.

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21
Q

What is a dihybrid cross?

A

It involves 4 possible gametes that have one allele of each gene.

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22
Q

How do you calculate the probabilities of the outcomes of dihybrid crosses?

A

You must multiply the outcomes from each of the individual monohybrid components.

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23
Q

What do humans genetics rely on?

A

Pedigrees.

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24
Q

What do pedigrees show?

A

they show phenotype segregation in several generations of related individuals.

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25
True or false. Human pedigrees show clear proportions.
False. Human pedigrees do not show clear proportions because humans have such small numbers of offspring.
26
What is autosomal dominant inheritance?
A pedigree analysis of the dominant allele for a given phenotype, which shows that : -Every affected person has an affected parent -half of the offspring of an affected person are also affected -the phenotype occurs equally both sexes.
27
What is autosomal recessive inheritance??
A pedigree analysis that shows for a given phenotype that: -If neither parent has a given phenotype, but it shows up in their progeny then the trait is recessive and their parents are heterozygous -half of the children from such a cross will be carriers -the chance of any one child getting the trait is 1/4
28
True or false. Different alleles exist because any gene is subject to mutation into a stable, heritable new form.
True.
29
True or false. Alleles mutate in a very specific order.
False. Alleles can mutate randomly.
30
Which is the most common allele in the population?
The wild type.
31
What are the alleles different from the wild type that can produce different fuel types called?
Mutant alleles.
32
How many alleles can a population have for a given gene?
More than two.
33
What is incomplete dominance?
When heterozygous mature, an intermediate phenotype, which might seem to support the blending theory. However, it is just the F2 progeny demonstrating Mandarin genetics.
34
What is codominance?
When two different alleles for a gene are both expressed in the heterozygotes.
35
What is pleiotropy?
When pleiotropic alleles, that are single alleles with more than one distinctinguishable phenotypic effect, then have unrelated characters caused by the same protein produced by the same allele.
36
What is epistatis?
Occurs when the alleles of one gene cover up or alter the expression of alleles of another gene.
37
What are complementary genes?
When two genes that are mutually dependent, have their own expression that depends on the alleles of the other.
38
In complementary genes, what do the recessive alleles code for?
They code for non-functional enzymes.
39
What Is Polygenic Inheritance?
it is complex inherited characteristics that are controlled by groups of several genes, called quantitative trait loci or polygenic inheritance.
40
41
What do the alleles of polygenic inheritance do?
They intensify or diminish the phenotype.
42
Describe the variation of polygenic inheritance.
-it is continuous or quantitive rather than qualitative -It is usually due to two factors: multiple genes with multiple alleles (polygenes), and environmental influences on the expression of these genes
43
What do homologous chromosomes exchange during prophase l?
They can exchange corresponding segments.
44
True or false. Genes that are close together tend to stay together.
True.
45
What are the progeny resulting from crossing over that appear in repeatable proportions called?
Recombinant theory.
46
Why are recombinant frequencies greater for loci?
They are farther apart on the chromosomes because a chiasma is more likely to cut between genes that are far apart.
47
What can recombinant frequencies for many pairs of linked genes be used for?
To create genetic maps.
48
How do scientist measure distances between genes?
In map units.
49
What does one map unit correspond to?
A recombination frequency of 0.01 or a centimorgan (cM).
50
In mammals which chromosomes do the females have?
Two X chromosomes.
51
In mammals which chromosomes do the males have?
An X and Y chromosome.
52
True or false. Disorders cannot arise from normal sex chromosome constitutions.
False. Disorders can arise from abnormal sex chromosome constitutions.
53
What is the Turner syndrome?
An XO condition that results in females that are physically or slightly abnormal, but mentally normal and usually sterile.
54
What is the Klinefelter syndrome?
An XXY condition that results in males that are taller than average and always sterile.
55
True or false. Some XY individuals lacking a small portion of the X chromosome are phenotypically female.
False. Some XY individuals lacking a small portion of the Y chromosome are phenotypically female.
56
True or false. Some XX individuals with a small piece of the Y chromosome are female.
False. Some XX individuals with a small piece of the Y chromosome are male.
57
What does the SRY stand for? What is it?
Sex determining region on the Y chromosome. It is the maleness-determining gene.
58
What does the SRY gene code for?
A functional protein.
59
What does the functional protein that SRY codes, tell the body to do?
it tells the body to develop testes. If it is not there, then the body develops ovaries.
60
What is gene on the X chromosome that is the maleness inhibitor?
DAX1
61
What does DAX1 produce?
Anti-testes factor.
62
How many genes are carried by the Y chromosome?
Very few (about 20).
63
How many genes are carried by the X chromosome?
A great variety.
64
True or false. Females with XX may be heterozygous for gene on the X chromosome.
True.
65
True or false. Males with XY have only one copy of a gene and are called heterozygous.
False. Males with XY have only one copy of a gene and are called hemizygous.
66
What inheritance does the hemizygous difference generate?
A sex-linked inheritance.
67
True or false. Genes on sex chromosomes do follow Mendelian patterns.
False. They do not follow Manion patterns and instead our governed by loci on the sex chromosomes..
68
A pedigree analysis of X-linked recessive phenotypes show that:
- The phenotype appears much more often in males than in females. -A male with the mutation can pass it only to his daughters. -Daughters who receive one mutant X are heterozygous carriers. -The mutant phenotype can skip a generation if the mutation is passed from a male to his daughter and then to her son.
69
A pedigree analysis of X-linked dominant phenotypes show that:
-The trait is never passed from father to son. -All daughters of an affected male and a normal female are affected. -All sons of an affected male and a normal female are normal. -Matings of affected females and normal males produce 1/2 the sons affected and 1/2 the daughters affected.
70
A pedigree analysis of Y-linked phenotypes show that:
-The trait is only passed from father to son.
71
True or false. Mitochondria, chloroplasts, and other plastids possess a small amount of DNA.
True.
72
True or false. Mitochondria and plastids are passed on by the mother only.
True. The egg contains the abundant cytoplasm and organelles.
73
A pedigree analysis of mitochondrial phenotypes show that:
-An affected mother passes the trait to all her children. -An affected father passes it to none of the children

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