Biology Chapter 14 Flashcards Preview

Biology > Biology Chapter 14 > Flashcards

Flashcards in Biology Chapter 14 Deck (85):
1

Who first studied genetics?

Gregor Mendel

2

When did Gregor Mendel study genetics?

1850 - 1870

3

What did Gregor Mendel use to study genetics?

Peas

4

Mendels genetic factors proved in 1952 to be

DNA

5

DNA is divided into

Genes

6

Each gene has the code for making what?

One protein

7

Human DNA has roughly how many genes?

25,000

8

Genes can be several alternative types called

Alleles

9

Examples of alleles are

Allele B for brown hair

Allele b for blonde hair

10

How many alleles do you inherit?

2 (one from each parent)

11

Dominant allele

Has an effect whether you have one copy or two (BB or Bb, brown hair)

12

Recessive allele

Only has an effect if you inherit two copies (bb, blonde hair)

13

Genetics

The study of inheritance

14

Genotype

The genetic makeup of an individual (Bb)

15

Phenotype

The physical appearance of an individual (brown hair)

16

Homozygous dominant

Two capital letters

17

Heterozygous

One capital, one lower case

18

Homozygous recessive

Two lower case letters

19

Mendel's first law of genetics

Different characteristics are caused by different alleles

20

Mendel's second law of genetics

An organism inherits two alleles for each trait

21

Mendel's third law of genetics

Each gamete only contains one allele for each trait

22

Mendel's fourth law of genetics

In a heterozygous individual, only the dominant allele affects the trait

23

Monohybrid cross how many traits are studied?

Only one trait is studied

24

Dihybrid cross how many traits are studied?

Two traits are studied

25

Test cross

Used to work out an unknown genotype (dominant phenotype)

26

What is the unknown genotype crossed with?

A homozygous recessive individual

27

If all the offspring have the dominant phenotype, the unknown parent must be

Homozygous dominant

28

If some of the offspring have the recessive phenotype, the unknown parent must be

Heterozygous

29

Dihybrid cross

Each trait is inherited independently

30

How many possible phenotypes in the dihybrid cross offspring?

Four

31

In a dihybrid cross, if two heterozygous individuals are crossed the result is a ratio of

9:3:3:1

32

Punnett squares work out the

Probability of getting a particular offspring

33

If two heterozygous individuals breed

3/4 of offspring will have the dominant trait and 1/4 will have the recessive trait

34

If two heterozygous people have children

Each child has a 1 in 4 (1/4) chance of being blonde

35

For a dihybrid cross

You multiply the probabilities together

36

Incomplete dominance

Both alleles affect the phenotype

37

Homozygous dominant (red) looks different from

Heterozygous (pink)

38

Both incomplete dominance alleles have

Capital letters

39

If two heterozygous individuals are crossed in a state of incomplete dominance the offspring are in the ratio

1:2:1

40

Polygenic inheritance

Trait is affected by several genes so the offspring of heterozygous parents can be very different from either parent

41

A graph of the expected offspring from heterozygous parents follows a normal distribution curve

Examples: skin color, height

42

Where are genes located?

Chromosomes

43

Different species have different numbers of --- but about the same amount of ---.

Chromosomes, DNA

44

A typical human chromosome has roughly how many genes on it?

1000

45

Linked genes are on the sam

Chromosome

46

Linked genes tend to be

Inherited together

47

How are linked genes separated?

By crossing over in Prophase I

48

What gives different results from the Punnett square prediction?

Linked genes being separated

49

How does a genetic map gives the location of genes?

By working out the frequency of crossing over

50

About what percent of a chromosome is genes?

10%

51

What percent of the originally unknown (junk DNA) is active?

80%

52

Most chromosomes consist of switches that turn what on and off?

Genes

53

How many genetic switches are in human DNA?

4 million

54

Non-sex chromosomes are called

Autosomal

55

How many pairs of non-sex chromosomes do both men and women human cells have?

22 pairs

56

How many pairs of sex chromosomes do human cells have?

1 pair

57

The sex chromosomes in the female are

XX

58

The sex chromosomes in the male are

XY

59

X chromosomes have how many genes?

Over 1000 genes

60

How many genes are in Y chromosomes?

Less than 80 genes

61

What percent of human births are male?

52%

62

What percent of human births are female?

48%

63

Why is there a higher percent of male births than female births?

Sperm carrying the Y chromosome are lighter and swim faster than ones with the X chromosome

64

Sex linked diseases mainly affect

Men

65

Sex linked diseases are caused by recessive genes on the

X chromosome

66

Women have --- copies of X while men have --- copies of X.

2,
1

67

Sex-linked diseases are usually passed on from a carrier female to her

Son

68

What percent of men are colorblind?

8%

69

What percent of women are colorblind?

0.5%

70

Hemophilia

Blood does not clot

71

How many X chromosomes are active in women?

1

72

What does the other X chromosome in women do?

Condensed to form the Barr body

73

Where is the Barr body?

The edge of the nucleus

74

Are the genes in the Barr body active or inactive?

Inactive

75

Heterozygous females can have different --- active in different parts of the body

X chromosomes

76

What are Barr bodies used for?

To test for gender in sporting events like the Olympics, to make sure competitors a really are female

77

Some genes have different effects depending on whether they are inherited from the mother or father. What are these genes called?

Genomic imprinting (the genes are imprinted)

78

During genomic imprinting,

Some of the fathers genes are switched off and some of the mothers genes are switched off

79

What will happen If two sperm or two eggs join

The embryo will not survive

80

Mice with mainly the fathers genes have

Small heads and large bodies

81

Mice with mainly the mothers genes have

Small bodies and large heads

82

Mice with male imprinted genes affect

Lower parts of the brain (feeding, reproduction, emotions)

83

Mice with female imprinted genes affect

The higher brain (thinking, memory)

84

Human male imprinted genes

Increase the size of babies

85

Human female imprinted genes

Reduce the size of babies