Genetics

Question 1

mitosis and meiosis were discovered when?

Answer 1

1875 and 1890s

Question 2

Mendel’s factors during sexual life cycles

Answer 2

• Chromosomes are present in diploid cells
• Homologous chromosomes segregate during meiosis
• Fertilization restores paired diploid condition

Question 3

According to chromosome theory of inheritance

Answer 3

• Mendelian genes have specific loci on chromosomes
  -Chromosomes undergo segregation and independent assortment

Question 4

Fruit fly experimentation

Answer 4

• the wild type allele was dominant
  -concluded that the eye colour gene must be located on the x-chromosome

Question 5

Humans have _____ pairs of chromosomes

Answer 5

23

Question 6

Of the 23 pairs of chromosomes 22 are _____

Answer 6

Homologous/autosome
(same size and contain the same genes)

Question 7

The 23rd pair of chromosomes are considered _____ and is called the _______

Answer 7

not a true pair
sex chromosomes

Question 8

Two varieties of the 23rd chromosome

Answer 8

X and Y
(XX = female)
(XY = male)

Question 9

The x-0 system

What creatures use this system?

Answer 9

22 + XX = female
22 + X = male

grasshoppers, crickets, and cockroaches, as well as some arachnids and nematodes

Question 10

The Z-W system

What creatures use this system?

Answer 10

76 + ZW = female
76 + ZZ = male

birds, some reptiles (like snakes and lizards), some insects (like butterflies and moths), and some fish and crustaceans

Question 11

The haplo-diploid system

What creatures use this system?

Answer 11

16 (diploid) = female
16 (haploid) = male

Hymenoptera (bees, ants, and wasps) and Thysanoptera (thrips), as well as sporadically in some spider mites, Hemiptera, Coleoptera (bark beetles), and rotifers

Question 12

When a female ovulates, the egg released contains

Answer 12

an x-chromosome
22 autosomes

Question 13

When sperm is produced it contains

Answer 13

22 autosomes
an x or a y chromosome

Question 14

What determines the sex of a child

Answer 14

the chromosome that the sperm carries

Question 15

Drosophila eye colour gene is an illustration of the principle…

Answer 15

genes that are located on the sex chromosomes do not necessarily have to do with sexual function

Question 16

Genes on human sex chromosomes that are completely unrelated to sexual function are called?

Answer 16

-sex linked genes

Question 17

Sex linked genes are commonly referred to as?
Because?

Answer 17

x-linked
in human terms the x-chromosome contains more important genes

Question 18

X-linked genes in humans follow the same pattern of inheritance that Morgan observed for the eye-colour locus in Drosophila, such as…

Answer 18

• generally males pass their x-chromosome to their daughters but not their sons
  -females pass 1 of 2 of their chromosomes to 1/2 daughter + sons

Question 19

Holandric genes

Answer 19

any gene located on the y chromosome

Question 20

X-linked dominant patterns
things that are always true:

Answer 20

a) affected males pass to all daughters, none of the sons.

b) affected females pass to at least 1/2 daughters and 1/2 sons

Question 21

How do X-linked genes and Holandric genes differ?

Answer 21

• Holandric genes are much smaller and contains fewer genes
• Holandric genes also have no x-counterpart and encode for traits only found in males
  (father to son)

Question 22

X inactivation in females

Answer 22

• prevents females from receiving a double dose of sex linked genes by inactivating one of the x chromosomes forming a dense dark object called Barr bodies

Question 23

Cells of females and males have the same ______ of genes on the _______–

Answer 23

effective dose
x-chromosomes

Question 24

The choice of which an X chromosomes inactivates occurs ______ and _______ in every cell

Answer 24

randomly
independently

Question 25

inactivation and the tortoise shell cat the tortoise shell genes is on the ______ and the phenotype requires the presence of __________

Answer 25

x chromosome two different alleles, one for orange fur one for black fur

Question 26

in tortoise shell cats Normally only _____ can have both alleles because they have ______

Answer 26

females two x chromosomes

Question 27

In tortoise shell cats if a female is heterozygous for the tortoise shell gene she is

Answer 27

tortoise shell

Question 28

Mosaicism

Answer 28

a condition where an individual possesses two or more distinct cell populations with different genetic makeup, arising from a single fertilized egg due to postzygotic mutation

Question 29

In humans, mosaicism can be seen in A heterozygous woman has

Answer 29

anhidrotic ecodermal dysplasia ( a skin disorder ) patches of normal skin and patches of skin lacking sweat glands

Question 30

Genetics is the study of

Answer 30

heredity - how traits are passed from parents to offspring

Question 31

The particulate theory of heredity was put forth by? In what year?

Answer 31

Gregor Mendel 1860's

Question 32

Gregor Mendel's theory of heredity

Answer 32

parents transmit physical factors (now called genes) to their offspring, which retain their identity in the offspring

Question 33

Another name for Gregor Mendel

Answer 33

the father of genetics

Question 34

In 1857 Mendel breed what...?

Answer 34

garden peas in the monastery abbey garden to study inheritance

Question 35

Why did Mendel choose garden peas as a model organism had several advantages

Answer 35

-Seven distinct varieties (seed shape, seed colour, pod colour, flower position, and stem length) -Characters varied in an "either or" manner (either purple flowers or white or either tall or short. no in between) -He could strictly control which plants mated with which -Easy and cheap grow

Question 36

True breeding

Answer 36

when cells always produce the same variety

Question 37

Law of Segregation

Answer 37

The two factors separate when the gametes are formed, and only one factor is present in each gamete

Question 38

Gene

Answer 38

A section of a chromosome that codes for a trait

Question 39

Locus

Answer 39

The position on a chromosome where a specific gene is located

Question 40

Allele

Answer 40

Two or more alternative versions of gene. They vary in nucleotide sequence

Question 41

Genotype

Answer 41

An organisms specific genetic composition; many times referring to a single gene

Question 42

Homozygous

Answer 42

An organism that has a pair of identical alleles for a gene

Question 43

Heterozygous

Answer 43

An organism that has two different alleles for a gene

Question 44

Phenotype

Answer 44

An organism's expressed traits

Question 45

When is the multiplication rule used?

Answer 45

to calculate the probability of two independent events occurring together

Question 46

When is the addition rule is used?

Answer 46

When any one of two or more mutually exclusive events will occur together is calculated by adding together their individual probabilities

Question 47

Pleotropic Gene

Answer 47

a single gene that has multiple phenotypic effects

Question 48

example of pleiotropic gene

Answer 48

albinism ( pale skin, hair and eyes)

Question 49

Epistasis

Answer 49

where a gene at one locus alters the phenotype produced by a gene at a second locus

Question 50

Polygenic Inheritance

Answer 50

where two or more genes control a phenotype

Question 51

skin colour in human is controlled by how many genes

Answer 51

3

Question 52

phenotype for a character depends on _________ as well as on genotype

Answer 52

the environment

Question 53

phenotype plasticity

Answer 53

capacity to develop traits suited to the environment experienced by an organism by varying patterns of gene expression