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Biology Chapter 14 Flashcards

(85 cards)

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1
Q

Who first studied genetics?

A

Gregor Mendel

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2
Q

When did Gregor Mendel study genetics?

A

1850 - 1870

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3
Q

What did Gregor Mendel use to study genetics?

A

Peas

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4
Q

Mendels genetic factors proved in 1952 to be

A

DNA

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5
Q

DNA is divided into

A

Genes

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6
Q

Each gene has the code for making what?

A

One protein

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7
Q

Human DNA has roughly how many genes?

A

25,000

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8
Q

Genes can be several alternative types called

A

Alleles

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9
Q

Examples of alleles are

A

Allele B for brown hair

Allele b for blonde hair

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10
Q

How many alleles do you inherit?

A

2 (one from each parent)

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11
Q

Dominant allele

A

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

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12
Q

Recessive allele

A

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

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13
Q

Genetics

A

The study of inheritance

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14
Q

Genotype

A

The genetic makeup of an individual (Bb)

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15
Q

Phenotype

A

The physical appearance of an individual (brown hair)

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16
Q

Homozygous dominant

A

Two capital letters

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17
Q

Heterozygous

A

One capital, one lower case

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18
Q

Homozygous recessive

A

Two lower case letters

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19
Q

Mendel’s first law of genetics

A

Different characteristics are caused by different alleles

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20
Q

Mendel’s second law of genetics

A

An organism inherits two alleles for each trait

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21
Q

Mendel’s third law of genetics

A

Each gamete only contains one allele for each trait

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22
Q

Mendel’s fourth law of genetics

A

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

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23
Q

Monohybrid cross how many traits are studied?

A

Only one trait is studied

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24
Q

Dihybrid cross how many traits are studied?

A

Two traits are studied

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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

Biology (19 decks)

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