Section 6: Heredity

Question 1

To determine the probability of two or more independent events occurring, what should be done with their individual probabilities?

Answer 1

Multiply them by each other

Question 2

This is the genetic material on a chromosome for a trait

Answer 2

Gene

Question 3

This is the location on a chromosome where the gene is located

Answer 3

Locus

Question 4

This is the variance of genes that can lead to different things like colors

Answer 4

Allele

Question 5

These are a pair of chromosomes that contain the same genetic material, gene for gene.

Each parent contributed 1 of the chromosome in the pair and thus different alleles may exist for a gene

Answer 5

Homologous chromosomes

Question 6

One member of each chromosome pair migrates to an opposite pole so that each gamete is _______ (aka each gamete has only one copy of each chromosome), occurs in anaphase I.

Answer 6

haploid

This is known as the law of segregation

Question 7

migration of homologues within one pair of homologous chromosomes does not influence
the migration of homologues of other homologous pairs (independent assortment of alleles)

Answer 7

Law of independent assortment

Question 8

This involves the breeding of a dominant trait individual with a recessive individual, in order to determine the zygosity of the former by analyzing proportions of offspring with the recessive phenotype. Determines if hetero or homo dominant.

These test one gene

These test two (on different chromosomes)

Answer 8

Test crosses

Monohybrid cross test

Dihybrid Cross Test

Question 9

What are the generations for test crosses?

Answer 9

P(parental), F1, F2 etc

Question 10

This is the blending of expressions of alleles, developing a unique hetero phenotype

ex:R red, R’ white, RR’ comes out pink

Answer 10

Incomplete dominance

Question 11

This occurs when both inherited alleles are completely expressed (e.g. blood types A and B or both can show up as AB if expressed)

Answer 11

Codominance

Question 12

Blood groups have 3 possible alleles, the codominant A and B and the O, leading to 4 possible genotypes
(phenotypes?): AO (A type), BO (B type), AB (codominant AB type), OO (O type

Answer 12

Multiple alleles

Question 13

One gene affects phenotypic expression of 2nd gene.

What’s an example of this?

Answer 13

Epistasis

Pigmentation

Question 14

In pigmentation, an example of epistasis, one gene is turn on/off and the 2nd gene controls the color amount. If the 1st gene codes for no pigment, does the 2nd gene have any effect?

Ex: CCBx => black fur in mice

ccxx =>no pigment

Answer 14

No.

Question 15

single gene has more than 1 phenotypic expression

For example, the gene in pea plants that expressed seed texture also
influences phenotype of starch metabolism and water uptake; sickle cell anemia leads to different health conditions

Answer 15

Pleiotropy

Question 16

The interaction of many genes to shape a single phenotype w/ continuous variation (height, skin color)

Answer 16

Polygenic inheritance

Question 17

two or more genes that reside on the same chromosomes and thus cannot separate independently because
they are physically connected (inherited together). They exhibit recombination about 18% of the time.

Answer 17

Linked Genes

Question 18

In a cross of BbVv x bbvv (says that BV and bv are linked and each is in a homologues). We only get BV or bv and no Bv or bV. However, if there is recombination, we may get 18% of Bv and bV

What does a greater recombination frequency mean?

Answer 18

Linked Genes

Farther distance of genes apart on the same chromosome

Question 19

In linked genes, Linkage map: B-V is 18%, A-V is 12%, and B-A is 6%, so what is the approximate spacing?

Answer 19

B——A————V ‘-‘ = 1 unit apart

Question 20

Refers to single gene resides on sex chromosome; when male (XY) receives an X from mother, whether it is
dominant or recessive will be expressed because there is no copy on the Y chromosome

Answer 20

Sex-linked

Question 21

can be influenced by sex of individual carrying trait (e.g. Bb female not bald, Bb male is)

Answer 21

Sex-influenced

Question 22

probability an organism with a specific genotype will express a particular phenotype`

Answer 22

Penetrance

Question 23

term describing the variation of phenotype for a specific genotype

Answer 23

Expressivity

Question 24

This occurs during embryonic development in female mammals, one of two X chromosomes does not uncoil into
chromatin

What is the dark and coiled compact body chromosome?

Can it be expressed?

Answer 24

X-inactivation

Barr body

No, so only the genes on the other X will be expressed.

Question 25

As an example of X-inactivation, calico cat females can be heterozygous for fur color, which usually leads to orange fur because the orange trait is dominant. But in females it can also lead to black. Why?

Answer 25

The dominant orange fur gene has been inactivated and turned into a barr body

Question 26

This is another example of X-inactivation, where the female cannot form a blood clot.

XHXh is a normal carrier, but if XH is inactivated, Xh is expressed

Answer 26

Hemophelia

Question 27

This is the failure of one/more chromosomes pairs or chromatids to separate during mitosis or meiosis

Answer 27

Nondisjunction

Question 28

Nondisjunction in meiosis or mitosis:

The failure of two chromatids of a
single chromosome during anaphase

Answer 28

mitosis

Question 29

Nondisjunction in meiosis or mitosis:

homologous chromosomes to separate during Meiosis I or sister chromatids to separate during Meiosis II;
result in trisomy or monosomy; ex Down syndrome

note: specifically during anaphase!

Answer 29

Meiosis

Question 30

This occurs cells that undergo nondisjunction in mitosis during embryonic development; fraction of body cells have extra or missing chromosome

Answer 30

Mosaicism

Question 31

This occurs all chromosomes undergo meiotic nondisjunction and produce gametes with twice the number of
chromosomes. Common in plants.

Answer 31

Polyploidy

Question 32

This is a human genetic defect where a single nucleotide changes causing substitution, insertion, deletion (latter 2 could cause frameshift).

Answer 32

Point Mutation

Question 33

This is a point mutation from purine to purine or pyrimidine to pyrimidine

This is a point mutation from purine to pyrimidine or vice versa

Answer 33

Transition mutation

Transversion mutation

Question 34

A genome with an extra/missing chromosome, often caused by nondisjunction (down syndrome = trisomy 21)

Answer 34

Aneuploidy

Question 35

This disease is nondisjunction in sex-chromosome. Gametes can be XX/XY or O (no chromosome). XO is sterile, physically abnormal. It may be missing on some or all

Answer 35

Turner Syndrome

Question 36

This genetic defect is marked by the XXY genotype

This is marked by Trisomy 21

Answer 36

Klinefelter

Down Syndrome

Question 37

These occur when chromosome segments are changed

This is repetition of a segment on the same chromosome

This is rearrangement of the segment in the reverse orientation

This is movement of the segment to another chromosome (can cause downs as well)

Answer 37

Chromosomal Abberations

Duplicatoins

Inversions

Translocation

Question 38

These are spontaneous or induced (mutagenic agents, Xrays). A deficiency means there was a lost fragment

Answer 38

Chromosomal Breakage

Question 39

These include cosmic rays, Xrays, UV rays, radioactivity, chemical compounds include colchicine (inhibits
spindle formation causing polyploidy), mustard gas. They are generally also carcinogenic

Answer 39

Mutagenic Agents

Question 40

Proto-oncogenes stimulate normal growth; if mutated become ____ which leads to cancer

Answer 40

Oncogenes

Question 41

AR genetic disorders include

The inability to product proper enzyme for phenylalanine breakdown; degradation
product phenylpyruvic acid accumulate

Answer 41

PKU

Question 42

AR genetic disorders include:

fluid builup in tracts

lysosome defect, can’t break down lipids for normal brain fxn

defective Hb due to substitution mutation

Answer 42

Cystic fibrosis

Tay-sachs

Sickle Cell Disease

Question 43

This genetic disorder results from degenerate nervous system tissue

This one is abnormal blood clotting

Also color blindness

Answer 43

Huntington’s disease

Hemophelia

Question 44

Which of these doesn’t typically cause mental retardation:

Downs, Turner, Klinefelter,

Answer 44

Turner’s syndrome

Question 45

This term means an already mutated organism mutates again even more

This one means it mutates back to the original

Answer 45

Forward mutation

Backward mutation

Question 46

Extranuclear genes are found in mitochondria and chloroplasts. Defects in mito DNA can reduce
cell’s ATP production. What type of inheritance is this?

Mitchondria passes to zygote all come from FATHER/MOTHER

Answer 46

Extranuclear inheritance

Mother

Note: mitochondria have their own ~70S ribosomes that make mitochondrial proteins within the mitochondrial matrix

Question 47

If the phenotype “skips” generations be suspicious of an….

If no skip, it is most likely

If a father doesn’t have a particular phenotype, none of his daughters display it in _______

Answer 47

Autosomal recessive disorder

Autosomal dominant

X-linked recessive

Question 48

This type of DNA is an exception an exception to the universality of the genetic code

Answer 48

Mitochondrial DNA