Mendelian Inheritance

Question 1

what is a trait?

Answer 1

a feature or characteristic of an individual

Question 2

what is your phenotype?

Answer 2

what is actually expressed or observed

Question 3

what is your genotype?

Answer 3

the set of genes/alleles for a particular trait

Question 4

what are qualitative traits?

Answer 4

the phenotype is either present or its not, often only a single gene

Question 5

example of qualitative trait?

Answer 5

ability to roll tounge

Question 6

what are quantitative traits?

Answer 6

the phenotype is expressed along a continuum, usually multiple genes involved, more complex patterns of inheritance

Question 7

example of quantitative traits?

Answer 7

skin color, weight

Question 8

what are alleles (variants)?

Answer 8

alternative forms of a gene (often more than 2 forms)

Question 9

example of an allele?

Answer 9

human ABO blood group system; persons with type AB blood have one allele for A and one for B

Question 10

what are homologous chromosomes?

Answer 10

• chromosome pairs, one from each parent, that are similar in length, gene position and centromere location
• carry the same gene in the same order, but the alleles for each gene may differ
• (1-22)

Question 11

what is homozygosity?

Answer 11

same alleles at a given locus

Question 12

what is heterozygosity?

Answer 12

different alleles at a given locus

Question 13

what are dominant alleles?

Answer 13

only one allele is expressed

Question 14

what are recessive alleles?

Answer 14

the weaker allele is not expressed unless both recessive alleles are present

Question 15

example of dominant alleles?

Answer 15

baldness, tougne roll, dimples

Question 16

example of recessive alleles?

Answer 16

most congenital diseases

Question 17

what is incomplete dominance?

Answer 17

when a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism’s resulting physical appearance shows a blending of both alleles
(the heterozygous phenotype is intermediate to those of either homozygote parent)

Question 18

example of incomplete dominance?

Answer 18

red flower and white flower breed to create pink flower

Question 19

what is co-dominance?

Answer 19

when two (or more) dominant alleles affect the phenotype in separate ways

Question 20

example of co-dominance?

Answer 20

AB blood type

Question 21

what is penetrance of a genotype?

Answer 21

the probability that a person exhibits a phenotype given the person has a genotype

Question 22

what is incomplete penetrance?

Answer 22

when the probability of having the disorder is significantly less than 100%

Question 23

what is variable expressivity?

Answer 23

a single gene results in a range of phenotypic values

Question 24

what is pleiotropism?

Answer 24

occurs when a single cell influences more than a single gene

Question 25

example of pleiotropsim?

Answer 25

marfan syndrome - disease affects more than one bodily tissue/organ

Question 26

what is Medels first law of segregation?

Answer 26

individuals posses two alleles and a parent passes only one allele to his/her offspring (matter of chance what allele is inherited)

Question 27

what is Mendels (second law) law of independent assesment?

Answer 27

alleles of different genes assort (get doled out) independently of one another during gamete formation (one gene/allele inheritance does not effect other gene/allele inheritance- it is independent)

Question 28

what is meiosis?

Answer 28

A special form of cell division in which each daughter cell receives half the amount of DNA as the parent cell

Question 29

what is recombination?

Answer 29

occurs early in meiosis and increases genetic diversity

Question 30

what can recombination be disrupted by?

Answer 30

linkage

Question 31

when does linkage occur?

Answer 31

when genes that are close to each other are assorted together during meiosis

Question 32

when are genes more likely to recombine?

Answer 32

genes that are further apart= more likely to be recombined

Question 33

what are some characteristics of sex-linked traits?

Answer 33

- greater in males - sons cannot inherit X allele from father (little father son resemblance of trait) - skip a generation - new mutations in gametes

Question 34

what does sex linked (X-linked) transmission involve?

Answer 34

genes found on the unmatched (Y) portion of the X chromosome

Question 35

what are some chromosome anomalles?

Answer 35

nondisjunction: uneven number of chromosomes divide (during gamete formation)

Question 36

most common chromosome anomally (nondisjunction)?

Answer 36

down syndrome

Question 37

what are expanded triple repeats?

Answer 37

unstable mutations involving a repeating sequence of DNA ex; CGG/CGG/CGG

Question 38

higher number of triple repeats = ??

Answer 38

more problems in functioning

Question 39

what is genetic anticipation?

Answer 39

successive generations show increasingly severe forms of the disease (usually because of triplet expansions)

Question 40

what is genomic imprinting?

Answer 40

expression of gene depends on whether it is inherited from mom or dad