1.2.2 - Non Mendelian Genetics

Question 1

• This occur when genes are close to each other on the same chromosome and do not segregate at random during meiosis
• It violates Mendel’s 2nd Law (Independent Assortment)
• Genes close on a chromosome are packaged into the same gametes and are said to be “linked”

Answer 1

Linkage

Question 2

It refers to the transmission of genes on the same chromosome

Answer 2

Linkage

Question 3

In Linkage, the common phenotypic ratio is ______

Answer 3

3:1

Question 4

• Who identified more than 50 genes on Drosophilia’s 4 pairs of chromosomes

Answer 4

Thomas Morgan

Question 5

Linkage maps were first developed by who?

Answer 5

Alfred Sturtevant

Question 6

• It is a map based on the frequencies of recombination between markers during crossover of homologous chromosome
• It shows the relative position of genes, as determined by how after two gene loci are inherited together

Answer 6

Linkage map

Question 7

Some DNA sequences are nearly always inherited together, like two inseparable friends. This nonrandom association between DNA sequences is called _________

Answer 7

Linkage Disequilibrium

Question 8

The human genome consists of many ________, where stretches of alleles stick together, interspersed with areas where crossing over is prevalent

Answer 8

LD blocks

Question 9

LD blocks, called ________, could be used to track genes in populations.

Answer 9

Haplotypes

Question 11

• It is a combination of alleles at multiple linked loci that are transmitted together
• It may refer to as few as two loci or to an entire chromosome depending on the number of recombination events that have occurred between a given set of loci
• “haploid genotype”

Answer 11

Haplotype

Question 12

It is a set of single nucleotide polymorphisms (SNPs) on a single chromatid that are statistically associated. It

Answer 12

Haplotype

Question 13

True or False

Sperm determines the sex of humans

Answer 13

True

Question 15

Genes on the Y chromosome are ________ and genes on the X chromosome are X-linked.

Answer 15

• Y-linked
• X-linked

Question 16

Y-linked traits are rare because the chromosome has few genes, and many of its genes have counterparts on the X chromosome.

Answer 16

True

Question 17

The Y chromosome has two pseudoautosomal regions namely _______ & ______ and has a large central area _______ that comprises about 95% of the chromosome and has only 22 genes

Answer 17

• PAR1
• PAR2
• Male-specific (non recombining) region (MSY)

Question 18

In the anatomy of the Y chromosome, the ________ determines the male sex

Answer 18

SRY

Question 19

In the anatomy of the Y chromosome, the ________ encodes a protein essential to producing sperm; mutations in it caused infertility

Answer 19

Azoospermia Factor (AZF)

Question 20

This chromosome includes 4% of all the genes in the human genome, but accounts for about 10% of Mendelian (single-gene) diseases

Answer 20

X-linked genes

Question 21

The human male is considered _________ for X-linked traits, because he has only one set of X-linked genes

Answer 21

hemizygous (1 g-bearing chromosome — 1 X chromosome)

Question 22

True or False

In females, X-linked traits are passed just like autosomal traits—that is, two copies are required for expression of a recessive allele and one copy for a dominant allele.

Answer 22

True

Question 23

True or False

• In males, a single copy of an X-linked allele causes expression of the trait or illness because there is no copy of the gene on a second X chromosome to mask the effect
• Man inherits an X-linked trait only from his mother

Answer 23

True

Question 24

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Always expressed in male

Answer 24

X-Linked Recessive Trait

Question 25

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Expressed in a female homozygote and very rarely in a female heterozygote

Answer 25

X-Linked Recessive Trait

Question 26

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Affected male inherits trait from heterozygote or homozygote mother

Answer 26

X-Linked Recessive Trait

Question 27

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Affected female inherits trait from affected father and affected or heterozygote mother

Answer 27

X-Linked Recessive Trait

Question 28

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Expressed in females in one copy

Answer 28

X-Linked Dominant Trait

Question 29

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Much more severe effects in males

Answer 29

X-Linked Dominant Trait

Question 30

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

High rates of miscarriage due to early lethality in males

Answer 30

X-Linked Dominant Trait

Question 31

Identify if it’s X-Linked Recessive Trait or X-Linked Dominant Trait

Passed from male to all daughters but to no sons

Answer 31

X-Linked Dominant Trait