Ch. 4 Extensions and Modifications of Basic Principles

Question 1

Autosomes

Answer 1

Nonsex chromosomes, which are the same in males and females

Question 2

XX Females and XO Males

Answer 2

in some insects, this is the genotypical system used.

absence or presence of second letter.

Question 3

ZZ Males and ZW Females

Answer 3

genotypical system found in birds, snakes, butterflies, some amphibians, and some fishes.

Question 4

pseudoautosomal regions

Answer 4

of the human X and Y chromosomes pair and recombine during meiosis. Thus genes in this region are not inherited in a strictly sex-linked fashion. PAR1 is located at the terminal region of the short arms and PAR2 at the tips of the long arms of these chromosomes.

Question 5

genic sex determination

Answer 5

sex is genetically determined but there ar no obvious differences in the genders chromosomes. genotypes at one or more loci determine the sex of an individual. found in some plants, fungi, protozoans, and fishes. (different from us - chromosomal sex determination- where the sex chromosomes look different in males and females)

Question 6

Chromosomal sex determination

Answer 6

humans determination of sex where the gene is located on Y chromosome and the sex chromosomes that carry those genes are different looking in males and females

Question 7

turner syndrome

Answer 7

often females. have underdeveloped secondary sex characteristics. affected women are short, low hairline, relitively broad chest, folds of skin on neck. most are sterile. genetype = XO

Question 8

Klinefelter syndrome

Answer 8

One or more Y chromosomes and MULTIPLE X chromosomes. Often XXY but some are XXXY, XXXXY, XXYY. Male, small testes and reduced facial and pubic hair. Often taller and sterile.

Question 9

Triple X syndrome

Answer 9

XXX, XXXX, XXXXX . Female traits but tall and thin. The XXX is normal inteligence but severity of intellectual disability increases with number of X chromosomes beyond 3.

Question 10

SRY gene

Answer 10

“sex-determining region Y” Y linked gene determines sex. if the gene is expressed then testosterone floods system and male characteristics develop.

Question 11

epistasis

Answer 11

phenomenon when the effect of gene interaction is that one gene masks (hides) the effect of another gene at a differnt locus.

Question 12

Epistatic gene

Answer 12

this gene does the masking

Question 13

hypostatic gene

Answer 13

the gene that gets masked.

Question 14

allelic

Answer 14

occuring at the same locus

Question 15

Complementation test

Answer 15

two recessive mutation homozygous parents mate and their offspring will be heterozygous with mutatnt allels (if occurs allelically). if they don’t express mutation but have wild type phenotype then Complementation occured.

Question 16

Complementation

Answer 16

has taken place if an individual possessing two recessive mutations has a wild-type phenotype, indicating that the mutations are nonallelic genes.

Question 17

sex limited characteristic

Answer 17

encoded by autosomal genes that are expressed in only one sex. the trait has zero penetrance in the other sex.

Question 18

sex influenced characteristic

Answer 18

determined by autosomal genes and are inherited according to Mendel’s principles but they are expressed differently in Males and females

Question 19

Cytoplasmic inheritance

Answer 19

some characteristics are encoded by genes located in the cytoplasm. Not all genetic material of a cell is found in the nucleus.

Question 20

complete dominance

Answer 20

White + Red = Red offspring

Question 21

incomplete dominance

Answer 21

white + red = pink

Question 22

codominance

Answer 22

white + red = some red parts some white parts

Question 23

penetrance

Answer 23

percentage of individuals having a particular genotype that express the expected phenotype 38/42 people having the allele for polydactaly. 38 were polydactylous. 98% penetrance.

Question 24

expressivity

Answer 24

degree to which the trait is expressed

Question 25

genetic maternal effect

Answer 25

the phenotype of the offspring is determined not by the individuals genotype but by the genotype of the mother.

Question 26

cytoplasmic inheritance

Answer 26

the cytoplasmic genes for a characteristic are inherited from ony one parent, usually the mother.

Question 27

genomic imprinting

Answer 27

genes whose expression is affected by the sex of one transmitting parent

Question 28

epigenetics

Answer 28

is the study of heritable changes in gene expression (active versus inactive genes) that do not involve changes to the underlying DNA sequence — a change in phenotype without a change in genotype — which in turn affects how cells read the genes.

Question 29

phenocopy

Answer 29

environmental factors alone can produce a phenotype that is the same as the phenotype produced by a genotype

Question 30

polygenic characteristics

Answer 30

characteristics encoded by genes at many loci

Question 31

pleiotropy

Answer 31

One gene affects multiple characteristics. EX: marfan syndrome (single mutation) cause long features, heart problems, and eye problems.

Question 32

discontinuous characteristics

Answer 32

Qualitative “one or other”

Question 33

continuous characteristics

Answer 33

Quantitative range

Question 34

Barr Body

Answer 34

condensed darkly staining bodies in the nuclei of cells. which is an inactive x chromosome.

Question 35

Lyon hypothesis

Answer 35

hypothesis that states Random inactivation of X chromosome in females. xx one active. xxx only one active. xxxx only one active therefore the rest are barr bodies. this is random inactivation though.

Question 36

GENOMIC IMPRINTING

Answer 36

We all inherit two copies of every autosomal gene, one copy from our mother and one from our father. Both copies are functional for the majority of these genes; HOWEVER, IN A SMALL SUBSET ONE COPY IS TURNED OFF IN A PARENT-OF-ORIGIN DEPENDENT MANNER. THESE GENES ARE CALLED ‘IMPRINTED’ because one copy of the gene was epigenetically marked or imprinted in either the egg or the sperm.