Chapter 8: Inheritance, Genes, and Chromosomes Flashcards Preview

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Flashcards in Chapter 8: Inheritance, Genes, and Chromosomes Deck (63):
1

Blending Inheritance

gametes contained "hereditary derminants (genessss)" that blended
think inks of different colors
short and tall = medium
smooth seed and wrinkled seed = intdeterminate
this would create the loss of parental characteristics
not real anymore

2

Particulate inheritance

when gametes fuse, each determinant was distinct and remained intact
wrinkled seeds and smooth seeds would have offspring with determinants for both

3

character

an observable physical feature
ex. seed shape

4

trait

a particular form of a character
ex. spherical or wrinkled seeds

5

true-breeding

when crossed wrinkled with another wrinkled, all wrinkled
homozygous

6

How did Mendel perform his experiments?

Step One: cut the stamen off one parental flower (why you may ask? so it can't self-fertilize)
step two: fertilize it with pollen from another flower with contrasting chracters
step three: plant the seeds from this pairing and watch them grow (write down traits and how many)
optional step 4: The F1 plants (in step three) self-pollinate and see what happens

7

Parental generation P

the truebreeding plants that mendel used in his experiment

8

First filial generation F1

the first offspring generation in Mendel's experiments

9

Second Filial Generation F2

the second offspring generation in Mendel's experiments

10

hybrid

the offspring of crosses between organisms differing in one or more characters

11

monohybrid

Mendel's F1 generation
the offspring between parental varieties with contrasting traits for a single character
smooth v. wrinkled

12

Dominant

the trait that "overpowers"

13

Recessive

the trait that will only be expressed if the gene for the dominant trait is not present

14

allele

different forms of a gene for particular characters
smooth seed allele vs wrinkled seed allele

15

Homozygous

two alleles that are the same
ex. two alleles for wrinkled seeds

16

Heterozygous

two alleles that are different
ex. one allele for wrinkled seedfs, another for smooth

17

Phenotype

the physical appearance of an organism

18

Genotype

genetic constitution of an organism

19

Law of Segregation

Mendel
when any individual produces gametes, the two copies of a gene separate, so that each gamete receives only one copy

20

Punnett square

with the blocks
grid
male gametes on top, female on the side

21

How is the recessive gene suppressed?

it can become mutated so it doesn't get transcribed and translated or encode a nonfunctinoal protein

22

Test cross

used to determine whether or not someone showing a dominant trait is homozygous
this is done by crossing them with an individual who is homozygous recessive for the trait (which isn't hard to identify becuase if they display the recessive phenotype then they are homozygous recessive)

23

Dihybrid cross

cross between indiciduals that are identical double heterozygotes
ex. two heterozygous smooth and yellow plants
9:3:3:1 ratio

24

Law of Independent Assortment

Mendel
alleles of different genes assort independently of one another during gamete formation

25

Basic conventions of probability

certain= probability of one
impossible= probability of 0
everything else in between

26

Pedigrees

family trees that show the occurence of inherited phenotypes in several generations of related individuals

27

What are the key things to look for in a dominant pedigree?

every person with the abnormal phenotype has an affected parent
either all (homozygous parent) or half (heterozygous parent) or the children in an affected family are affected

28

What are the key things to look for in a recessive pedigree?

Affected people often have two unaffected parents
about one fourth of children of unaffected parents in affected families are affected

29

Mutations

rare, stable, and inherited changes in the genetic material

30

True or false: an allele can mutate to become a different allele

true

31

What affects the prevalence of a new allele?

the fitness of the individuals carrying it

32

wild type

THE ALLELE THAT IS PRESENT in most of the individuals in nature

33

Mutant alleles

the not wild type

34

Polymorphic

a gene with a wild type allele that is present less than 90% of the time

35

Incomplete dominance

alleles are not dominant or recessive to one another
heterozygotes have intermediate phenotypes
red and white makes pink

36

Codominance

two alleles of a gene both produce phenotype when present in a heterozygote
ex. AB blood type

37

Epistasis

the phenotypic expression of one gene is affected by another
ex. labsssss (such cuties)
Ee or EE other gene is good to go
ee, other alleles turned off

38

Hybrid vigor (heterosis)

Darwin- corn offspring produced by different genetic barieties are tall
Shull- they are also heavier

39

Quantitative traits

traits conferred by multiple genes
must be measured, not assesed qualitatively

40

True or false: most complex phenotypes are determined by multiple genes

true

41

True or false: the phenotype of an indivdual results from its genotype alone

falsee
genotype and environment interact to create phenotype

42

Penetrance

the proportion of individuals in a group with a given genotype that actually show the expected phenotype
helps describe the eggects of genes and enviro on phenotype
ex. not everyone with the mutant BRCA1 develops breast cancer--> incompletely penetrant mutation

43

Expressivity

degree to which a genotype is expressed in an individual
ex. one person with BRCA1 may have breast and ovarian cancer, another just breast cancer, so it has variable expressivity

44

locus

a particular site on a chromosome where a particular sequence of DNA (gene) resides

45

`Thomas Hunt Morgan

gene linkage
Columbia University
Fruit fly experiments

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Morgan Experiments with fruit flies

he did a test cross with two known genes B and Vg for wing shape and body color
expected 1:1:1:1 of different phenotypes
often the two traits were inherited together
loci linked on same chromosome
crossing over makes the coupled inheritance not absolute

47

recombination frequency

the number of recombinant progeny divided by the total number of progeny
greater for loci that are father apart on a chromosome, which means they

48

genetic linkage

association between genes on a chromosome so that they do not exhibit random assortment and only rarely recombine
the closer they are, the lower the frequency of recombination

49

autosomes

regular chromsomes (these pairs are similar in size to one another)

50

sex chromsomes

determine the sex of an individual

51

What are two differences between x and y chromsomes?

size
more genes are present on the x than the y

52

hemizygous

a gene that is present as a single copy in a diploid organism

53

sex-linked inheritance

inheritance of a gene that is carried on a sex chromosome

54

patterns of sex0linked recessive phenotypes

appears a lot more in males than females (men only need one copy)
men can only pass mutation to daughters (sons get the y chromosome)
daughters with one x linked mutation are heterozygous carriers
mutant phenotypes can skip a generation if it passes from father to daughter to son

55

Heterozygous carriers

phenotypically wild type, but can pass on mutant allele to children

56

True or false: the only organelle with genetic material in the cell is the nucleus

false
mitochondria and plastids

57

True or false: the inheritance of organelle genes differs from that of nuclear genes

true
mitochondria and plastids only inherited from mother (sperm only bring nucleus to fuse, no organelles)

58

Cytoplasmic inheritance

the inheritance of organelles and genes
come from maternal cytoplasm

59

True or false: prokaryotes can transfer genes from one to the other

truee

60

Bacterial conjugation

happens via physical contact initiated by the sex pilus
material then passes through a conjugation tube (JUST ONE WAY FROM DONOR TO RECIPIENT)
once inside, it can recombine
donor DNA can line up beside homolgous genes and cross over
genes from donor can be integrated and change the recipients genetics
only about hald of transfered genes become integrated, the integrated ones are passed on

61

sex pilus

extends from the donor prokaryotic cell to the recepient prokaryotic cell, initiating contact and gene transfer

62

Plasmids

smaller, circular DNA in bacteria
have a few dozen genes tops
generally these genes are for:
unusual metabolic abilities (like breaking down hydrocarbons)
antibiotic resistance (plasmids with these are R factors and are really dangerous)

63

True or false: plasmids transfer genes between bacteria

true
they can move between cells during conjugation
don't need to recombine with main chromsome because they copy separately