Genetics Flashcards Preview

Biology 101 > Genetics > Flashcards

Flashcards in Genetics Deck (123):
1

The study of the process by which information is transmitted from one generation of living things to the next

Genetics

2

Every living thing is organized via coded information, called

(Same word) Reproduction involves duplication and transmission of an organisms _______.

Genetic Material

3

An information entity. It is a sequence of DNA that codes for a single genetic instruction

Usually, this instruction is the sequence of a protein, but a gene may also serve to activate or deactivate other genes, in a cell, or in neighboring cells.

Gene

4

Every aspect of our species is constructed based on information encoded in

By themselves do very little, they are information storage molecules. It is the cytological machinery of our cells, passed from one generation to the next, that translate these instructions into a living organism.

Genes

5

The effects of every gene depend both upon other genes, and upon the environment.

Word!

6

ONE variant of a gene. Many genes have two, several, or many different variants of the same basic genetic information.

Allele

7

T/F: Some alleles are minor differences that to not significantly affect the organism, others cause profound changes.

True

8

Nucleotide substitutions in which codon position often produces no change at all, because they code for the same transfer RNA and thus the same protein is produced

Third Codon

9

Ex: humans…CCUv=>CCA does not cause a change, both triplets code for proline.

mkay

10

Other substitutions may produce profound effects, sickle cell anemia is caused by a single nucleotide substitution: GAG => GUG. What does it cause?

Normal hemoglobin sickles, or has an abnormal shape and becomes rigid, under low oxygen concentrations

11

the simplest, oldest, and most common organisms on the planet.

Prokaryotes (Archea and Bacteria)

12

A typical prokaryote has a much smaller genome than a typical eukaryote, nearly always it's in the form of what?

Note: It's still a lot of DNA in a single bacterium, stretched out it is 500 times longer than itself

a simple loop of DNA with associated proteins

13

Where is the DNA loop in prokaryotes attached?

To the cell membrane

14

Do prokaryotes have sexual reproduction?

Do they have gene exchange?

No.

Yes. Ex: Swapping plasmids.

15

Is there a functional grouping to the order of genes arranged along the length of the chromosome?

No, evolutionary chance determines it.

16

In prokaryotes, the DNA loop replicates before fission with both loops where?

Attached to the cell membrane

-One loop of DNA ends up in each new daughter cell.

17

Most eukaryotes have how much more DNA than a typical prokaryote?

Several orders of magnitude

18

Eukaryote genes are arranged along the length of a chromosome, like prokaryotes. Is their a functional reason for their location on the chromosome or which they're on?

No, it's an evolutionary accident.

19

Eukaryote DNA is usually circular or linear?

What is one exception

Linear

Plastid DNA - similar to bacterial DNA

20

What are the linear strands of DNA called?

Where are they packed?

Chromosomes

The nucleus

21

In multicellular eukaryotes, does every cell have the same DNA?

Yes

22

What explains differences in function between cells?

Only a fraction of the genes are active in certain cells.

23

These are very important and very evolutionarily conservative proteins. Loops of DNA are wrapped around one of them and locked in

Histones

24

What locks in the loops of DNA and histones?

Nucleosome

25

duplication of the genetic material within a eukaryote cell in which a cell gives rise to two smaller but genetically identical copies of itself

Mitosis

26

Mitosis can lead to growth in a what type of organism?

Mitosis can lead to asexual reproduction in what type of organism?

Multicellular

Single Celled

27

Is mitosis a means of producing gametes?

No.

28

In sexual organisms, what does mitosis do?

Gives rise to cell types which kill themselves off by splitting and splitting again into four very different cells

29

a particular type of reproduction, a sharing of genetic material, to form an individual with equal contributions from two separate parents.

Sexual Reproduction

30

A haploid sex cell that is formed from a diploid cell during meiosis

Gamete

31

A combination of genetic information from two separate cells to form a diploid cell (aka zygote)

Syngamy (fertilization)

32

Sex probably evolved as a means of producing variable offspring in the face of an uncertain future, though its evolutionary origins are obscure.
It is virtually ubiquitous among eukaryotes, though many can produce sexually or asexually.
It has the potential to produce enormously variable sets of genetic information, something that can be crucial to the survival of a species.

K

33

In some organisms, the haploid phase of the life cycle is multicellular, and haploid individuals simply grow together during the process of syngamy

K

34

the state of having two copies of every single gene -like pairs of shoes, pairs of gloves, pairs of stereo speakers.

Diploidy

35

Flies, Zebras potatoes, and humans are haploid or diploid?

Diploid - we have two copies of every gene in our bodies

36

Identically matched copies of a gene

homozygous

37

Subtly different copies of a gene

heterozygous

38

Are all organisms diploid as adults?

No, some are haploid.

39

For sexual reproduction to occur, there must be a haploid and diploid phase of the life cycle.

Word.

40

The process by which a single diploid cell gives rise to four, genetically different, haploid cells.

Meiosis

41

The diploid progenitor duplicates its genetic material…thus, every chromosome is composed of two, identical...

chromatids

42

Where are the two chromatids joined?

Centromere

43

Each chromosome finds its match, to form “matching pairs” of homologous chromosomes. This process occurs during the first of the two meiotic divisions. Does this occur during mitosis?

No, it is unique to meiosis

44

The four stands cluster in structures called _____ along the center of the dividing cell

Tetrads

45

These drag each side of each chromosome to the opposite poles of the cell.

Spindle Fibers

46

Is where a chromosome ends up planned or random?

Is it influenced by the fate of the other chromosomes around it?

Random.

No.

47

The cell divides and the spindle fibers once more drag them to othe opposite poles of the cell. The cell then divides.

How many genetically different daughter cells are formed?

4.

48

Are the four cells haploid or diploid?

Haploid

49

What does meiosis create?

What does it ensure in offspring?

Gametes (sperms and eggs)

Variability

50

Errors in meiosis have the potential to produce unusual phenotypes in the offspring

The most common meiotic error causes an entire homologous pair of chromosomes to migrate to the pole of the cell without splitting. This is called..
- produces triploid or even tetraploid offspring

Nondisjunction

51

If nondisjunction happens to a single pair, it causes....

Trisomy or monosomy in teh offspring

52

This human condition results from trisomy at chromosome 21

Down's syndrome

53

Note: trisomies at chromosome 18, 13, and 23 are also survivable

K

54

In humans trisomies for other chromosomes are usually not viable. What about other organisms, can triploids and tetraploids be viable?

Yes.

55

starts with a single diploid cell with two redundant sets of DNA, and produces four haploid cells, each with a single set of DNA.

Meiosis

56

Meiosis produces variation in two ways.
By randomly selecting one, or the other, chromosome from a diploid set, to form a haploid set, an enormous number of potential gametes arise. In an organism with 23 pairs of chromosomes, for instance, 2^23 potential gametes can be formed this way. This phenomenon is called

Assortment

57

This is a result of crossing over, where new combinations of alleles on chromosomes may arise.

Recombination

58

a cytological phenomenon that occurs during the first of the two meiotic divisions where two strands of DNA from complimentary chromosomes cross over each other, and a break forms.

The break is quickly repaired, switching stretches of DNA among the two compliments to create two new chromosomes

Crossing Over

59

A pair of chromosomes can cross over once, several times, or not at all. The farther apart two genes are on a chromosome, the MORE OR LESS? likely it is that crossing over will create recombination between the two of them.

The farther apart two genes are on a chromosome, the more likely it is that crossing over will create recombination between the two of them

60

This term means location, and it refers to the place where variation can occur

Locus

61

Using this word emphasizes its information content.

Gene

62

Does meiosis produce new genes or alleles?

No, just new combinations of chromosomes and new combinations of alleles on chromosomes

63

the process by which a gamete comes to have only one of the two alleles its parent possesses, for every gene. It is random, and it occurs because of the separation of homologous chromosomes during the first meiotic division.

Segregation

64

accounts for the fact that most eukaryotes possess many pairs of chromosomes, it is segregation at two or many loci simultaneously. Assortment is responsible for the variation in gametes created by the random selection of chromosome from each pair into gametes..

Assortment

65

When genes are on separate chromosomes, it is said that they assort independently. When they are on the same chromosome, they tend to get passed on as a unit, which can only be broken up by recombination, this is called

Linkage

66

The white-cheeked rosella
exhibits four varieties,
each with its own distinct
color combination and
markings.
The diagram shows where
these varieties are found.

Question-Based upon this
information alone, can you
Tell whether the variation
is genetic, environmental,
or both?

??

67

or qualitative variables, can be scored, but not fall into a continuum.
Examples: human eye color, political party, blood type, gender, etc..

Attributes

68

or measurable, variables fall along a measurable axis, and can be measured to observe their place relative to others.

Quantitative variables

69

fall into discrete intervals. Examples: shoe size, number of mates, number of arrests for drunk driving, etc..

Discontinuous Measurable Variables

70

do not fall into discrete intervals, they exist along a continuum. Examples: height, weight, age, etc..

Continuous measurable Variables

71

This reflects the number of individuals in a group possessing each value for the trait.

Distribution of Values

72

The group of individuals in question is the ______, the population has a distribution of values for the variable

Statistical Population

73

These distributions are frequently expressed as a ______:the range of values for the category is broken into intervals, and the number of individuals within that interval is expressed as the height of a bar

Histogram

74

In the albino coat color in mice, is the albino allele dominant of recessive?

Recessive

75

Example of rare recessive alleles of medical interest: A rare, autosomal recessive allele on chromosome 7 disrupts the normal migration of neurons, leading to an abnormally thick and smooth cerebral cortex, and reduced cerebellum, hippocampus, and brainstem causing a condition called.....

-they normally have normal parents

Lissencephaly

76

a condition where the affected individual has severely deformed digits, is caused by a dominant allele (there is a recessive syndrome that produces a similar condition).
It runs in families, conspicuously, and was passed from the famous circus performer, Grady Stiles Junior, to one of his offspring.

Ectrodactly

77

the allelic interaction where, in the heterozygous state, both alleles are expressed (for attributes), or the heterozygote is in between the phenotypes of the homozygous individuals for those alleles (in the case of measurable characters).
Thus, the heterozygote has a unique phenotype.

Codominance

78

For example, in chickens, black feather color (FBFB) is codominant with white feather color (FWFW). Heterozygous chickens (FBFW) have black and white feathers in a checkered pattern.

Cooooool

79

The human ABO locus has three loci, which exhibit both dominance and codominance.
Human blood types are encoded by a single locus with three alleles: IA, IB, and i0.
IA and IB code for two different proteins, cell surface antigen A, or antigen B. i0 codes for the lack of that particular protein.
Since we are diploid, we have a blood type, a phenotype, that depends upon the proteins on the surface of our blood cells. IaIa=? IaIo=?IbIo=?IbIb=? IoIo=?

IaIa=A IaIo=A

IbIo=B IbIb=B

IoIo=O

80

IA and IB are therefore _______with respect to each other, and both are ______ with respect to i0.

Codominant, dominant

81

Most traits are not coded by a single gene…the Rh+/Rh- status of an individual is coded by at least two loci, RhD and RhCE..
Having a dominant allele at either of these loci makes a person.....
Having recessive alleles at all Rh loci makes a person....

Rh+
Rh-

82

An organisms observable characteristics
An organisms genetic composition of alleles

Phenotype
Genotype

83

Bacteria have about ____ genes
Yeast have about ______ genes
Drosophila melanogaster have about
Human beings have an estimated ____ protein coding genes

1,200
5,000
10,000
24,000

84

Note: for humans, Regulatory genes-genes that modify the action of protein-coding genes, are much fewer in number, but harder to nail down.

Cool

85

Do all loci have multiple alleles?

No, perhaps 1-5% of loci have multiple alleles, depending upon the species

86

Is the vast majorit of DNA genes?

No, it is non-transcribed junk DNA of uncertain or no function

87

describes the pattern of phenotypic expression of a particular genotype across different environments.

Norm of reaction

88

For example, in yarrow, tall plants grow at low elevation roadsides, and much shorter plants grow in the mountains.

Norm of reaction

89

Differently adapted local varieties of a species are called...

One may perform well in one situation but might perform very poorly in another environment

Ecotypes

90

He conducted experiments on the garden pea, Pisum sativum, a species that exhibits variation for several interesting characters: pod color, seed color, flower color, height, etc.. These differ because of alleles at a single locus.
Garden peas also produce a large number of offspring, a key to Mendel’s success.

Gregor Mendel

91

Mendel was among the first scientists to think in ____ rather than strictly qualitative terms

Quantitative

92

Mendel discovered that inhertence is _____:

“particles” called genes carry the information that makes parents tend to resemble their offspring.
This was a huge departure from the previous scientific paradigm, believed for centuries, that inheritance was somehow carried in the blood and blended together every generation.

93

These “particles” segregate, so that individuals with two particles produce gametes with only one particle, the

The law of segregation

94

The “particles” for each gene segregate independently of each other, called the

This law is, of course,not universal. It applies only to the special case where genes are on separate chromosomes. It was not until decades later that the relationship between chromosomes, and Mendel’s particles, was discovered.

law of independent assortment

95

Two lines of garden peas have been grown separately for a long time, they are called _____

lines because the parents always resemble the offspring.

96

The segregation of alleles into gametes follows the laws of probability: therefore an Aa individual would produce 50% A gametes and 50% a gametes. If genes are on different chromosomes, alleles assort independently of each other

The law of independent assortment

97

The number of potential, different, gametes a parent can produce is equal to

Thus, a heterozygote for three loci: Aa Bb Cc could form ____ different gametes

2^N
where N is the number of loci assorting

8

98

____ causes certain combinations of alleles to be over-represented in the gametes.

Linkage

99

the result of two loci being located close together on the same chromosome. It causes a departure from independent assortment (thus, Mendel’s second law is incorrect, but he didn’t know about chromosomes).

Linkage

100

You can tell how far apart loci are by the proportion of the F2 from a test cross that are recombinants. Simply take the number of recombinants and divide by the total, and that gives you r-the proportion of recombinants

!

101

r=
map units =

# of recombinants/total offspring
Distance in map units (Morgans)

102

The linkage groups almost always turn out to be

Chromosomes

103

In Primula sp, an interesting genetic system maintains two distinct phenotypes in the population, and ensures the virtual absence of intermediate phenotypes

each type of flower is well adapted to cross with its opposite, but unable to cross with itself, called

Heterostyly

104

Heterstyly encourages ____, which can potentially maintain genetic diversity

Outcrossing

105

G allele codes for
g allele codes for
A allele codes for
a allele codes for
P allele codes for
p allele codes for

Short Style
Long Style
Long anthers
Short anthers
Thrum pollen
Pin Pollen

106

In normal populations, only two genotypes are present, GgAaPp, and ggaapp

Why are the other possiblities rarely seen?

Linkage
Mechanical impossibility of thrum x thrum croses
-Thrun pollen cannot grow down a short style

107

Each form is adapted to transfer pollen to a different part of the potential pollinator

Thrums transfer pollen to ____ which can be received by the styles of a pin flower

Pins transfer pollen to the ____ which can by received by the styles of a thrum flower

Waist
Head

108

Rare crossing over events, in thrum flowers, produce intermediate phenotypes, but these do not do not produce many offspring of their own, at least via animal pollinators

Word booty.

109

is not really linkage; is the term for a locus being located on a sex chromosome, such as the X chromosome in humans or Drosophila

It causes a unique combination of inheritance.

Sex linkage

110

Recessive alleles are therefore automatically expressed in the male, a state referred to as the

Hemizygous condition

111

the sex containing two like sex chromosomes. In most animal species these are females (XX).
Butterflies and Birds, ZZ males

Homogametic sex

112

the sex containing two different sex chromosomes In most animal species these are XY males.
Butterflies and birds, ZW females.
Grasshopers have XO males.

Heterogametic sex

113

In ants, bees, and wasps, males are haploid, in effect, every locus is sex-linked.

Word.

114

These are all examples of, which exhibit a characteristic pattern of inheritance:

Hemophilia
Duchenne’s Muscular Dystrophy
Red-Green Color Blindness

Sex-Linked Traits in humans

115

Which are more commonly affected by those genes?
In which does the allele occur more frequently?

Males
Females

116

One key indicator of sex-linkage is that reciprocal crosses give different results

Okay

117

occurs when a gene at one locus alters the expression of a gene at another locus.

Epistasis

118

Genes that exhibit this when they have multiple effects

Pleiotropy

119

Marfan's Syndrome is an example of ______, where individuals have the potential for: very tall stature, elongated fingers, curved spine, problems with their retina, heart valve problems.

Pleiotropy

120

All effects of Marfan's syndrome result from an allele that affects the distribution of ______molecule. It's fibers surround important areas of connective tissue, and therefore modified fibrillin causes many changes.

Pleiotropy

121

describes the probability that, given a genotype, the individual in question will manifest it.

Ex: Huntington's disease is caused by domninant allele. 95% of ppl with it manifest it, 5% do not

Penetrance

122

the extent to which a trait is manifest, given that it is manifest in an individual. Many traits have variable amounts of it.

For example, Marfan Syndrome, some people develop a tall build and long fingers, others develop life-threatening conditions.

Expressivity

123

Having a particular genotype does not necessarily mean the individual will manifest it. Also, it is possible to manifest a trait to various degrees.

In other words, researches perform genetic crosses under unreal conditions. In the real world, alleles do not act alone, they act in concert with other genes and against a variable environmental background.

WORD!