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Biology > Chapter 3 - Genetics > Flashcards

Chapter 3 - Genetics Flashcards

1
Q

genetics

study of..

A

how traits are inhereted from one generation to the next

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2
Q

basic unit of heredity

A

gene

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3
Q

genes composed of

A
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4
Q

genes are located on the

A
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5
Q

alleles

A

genes existing in more than one form

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6
Q

genotype

A

genetic makeup of an individual

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7
Q

phenotype

A

physical manifestation of genotype

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8
Q

phenotypes can correspond to a single or several of these

A

genotypes

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9
Q

Gregor Mendel

A

1860s

basic principles of genetics

garden pea experiments

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10
Q

garden pea experiment

A

inheritance of individual pea traits by performing genetic crosses

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11
Q

genetic crosses

mendel’s pea experiments

A

true-breeding individuals with different traits

mated them

statistically analyzed inheretance of traits in progeny

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12
Q

mendel’s first law

A

law of segregation

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13
Q

mendel’s four postulates of inheritance

(law of segregation)

A
  1. genes exist in alternative forms (alleles)
  2. organism has two alleles for each inherited trait, one from each parent
  3. two alleles segregate during meiosis —> gametes carry one allele for any given trait
  4. two alleles in individual are different - only one expressed, other is silent
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14
Q

dominant allele

A

allele which is expressed

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15
Q

recessive allele

A

allele which is silent in presence of dominant allele

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16
Q

homozygous

A

organisms that contain two copies of same allele

homozygous for that trait

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17
Q

heterozygous

A

organisms that carry two different alleles

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18
Q

Mendel’s law of dominance

A

dominant allele appears in phenotype

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19
Q

monohybrid cross

(mendel’s first law - law of segregation)

A

only one trait studied in particular mating

(i.e. color)

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20
Q

Parental or P Generation

(mendelian genetics)

A

individuals being crossed

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21
Q

filial / F generation

A

progeny generations

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22
Q

Punnett Square Diagram

(Mendel’s First Law - Law of Segregation)

A

used to predict genotypes expected from a cross

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23
Q

Testcross

Reasoning

(Mendel’s First Law - Law of Segregation)

A

genotype can only be predicted from recessive phenotype

dominant phenotype - homozygous or heterozygous

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24
Q

testcross

used to

A

determine unknown genotype of org with dominant phenotype

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25
Q

test cross

(aka back cross)

definition

A

organism with dominant phenotype of unknown genotype (Ax) crossed with phenotypically recessive organism (genotype aa)

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26
Q

results of test cross

A

P: AA x aa

F1: 100% Aa; 100% dominant phenotype

P: Aa x aa

F1: 50% Aa; 50% dominant phenotype

50% aa; 50% recessive phenotype

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27
Q

Mendel’s Second Law

A

Law of independent assortment

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28
Q

law of independent assortment

(principle)

A

law of segregation applies as long as genes are on separate chromosomes and assort independently

genes on same chromosomes stay together unless crossing over occurs

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29
Q

law of independent assortment

dihybrid cross

A

P generation:

purple flower tall pea plant (TTPP)

x

white flowered dwarf pea plant (ttpp)

F1 progeny - TtPp genotype

dominant phenotype

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30
Q

crossing over

(application to law of independent assortment)

A

crossing over may break linkage of certain pattern

i.e. redheads + freckles; sometimes blondes have freckles

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31
Q

Dihybrid Cross

F1 Generation

A

F1 Generation self crossed

TtPp x TtPp

4 phenotypes

9:3:3:1

(sorts as it would in monohybrid:

3:1 ratio favor dominant)

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32
Q

Non-Mendelian Inheritance

Complications with Mendelian

A

Genotype doesn’t translate into phenotype 100%

not 100% of recessive phenotype have 100% recessive genotype

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33
Q

Incomplete Dominance

(complications with mendelian genetics)

A

phenotype of heterozygote is intermediate of phenotypes of homozygotes

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34
Q

incomplete dominance

example:

snapdragon flowers

A

P: RR x rr

(red x white)

F1 genotypic ratio: 100% Rr

F1 phenotypic ratio: Rr = pink

F1: Rr x Rr

(pink x pink)

F2 genotypic ratio: 1 RR: 2 Rr: 1 rr

F2 phenotypic ratio: 1 red: 2 pink: 1 white

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35
Q

Codominance

(non-mendelian inheritance)

A

multiple alleles exist for given gene

more than one is dominant

each dominant allele fully dominant when combined with recessive

two dominant alleles:

phenotype is result of expression by both dominant alleles simultaneously

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36
Q

Codominance

example:

ABO blood groups

A

Blood type determined by three alleles:

IA, IB, i

only 2/3 allele present in individuals

all alleles present in human population

IA, IB - dominant

i - recessive

IAIA or IAi - blood type A

IBIB or IBi - blood type B

ii - blood type O

IAIB - blood type AB

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37
Q

Sex Determination

(Mendelian genetics)

A

for every mating event, 50% chance boy, 50% girl

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38
Q

autosomes

A

non sex chromosomes

22/23 chromosome pairs

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39
Q

sex chromosomes

A

1/23 pairs

determine sex of organism

females - XX

males XY

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40
Q

gender determination

A

females produce only X chromosome

male determine gender of zygote - produce X or Y

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41
Q

sex linked chromosomes

A

genes located on X or Y chromosomes

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42
Q

most sex linked chromosomes carried on the ___ chromosome

A

X chromosome

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43
Q

Sex Linkage

(Mendelian Genetics)

A

recessive genes carried on X chromosome will produce recessive phenotype in males

(only one X)

no dominant allele present to mask

recessive phenotype much more common in males

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44
Q

examples of sex linked recessives

A

hemophilia

color-blindness

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45
Q

sex-linkage inheritance

A

affected males pass on trait to all daughters (X), no sons (Y)

can be passed from father to grandson via carrier daughter

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46
Q

Drosophila melanogaster

A

helped provide explanations for mendelian genetic patterns

advantages for genetic research

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47
Q

Advantages of Drosophila melanogaster for genetic research

(5)

A
  • reproduce often (short life cycle)
  • reproduce large numbers
  • large chromosomes
  • few chromosomes (4 pairs; 2n=8
  • frequent mutations
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48
Q

analyses of D. melanogaster led to discoveries

(2)

A

pattners of embryological dev.

how genes expressed in early dev affect adult organism

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49
Q

Environmental Factors

(Mendelian Genetics)

A

interaction between environment and genotype produces phenotype

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50
Q

Enviornmental factors in genetics and Drosophila

A

with given set of wings:

crooked wings at low T

straight wings at high T

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51
Q

environmental factors in mendelian genetics in Himalayan hare

A

same color genes

white on warmer parts of body

black on colder parts of body

(if naturally warm parts cooled with ice, hair will grow black)

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52
Q

Genetic Problems

A

chromosome number and structure maybe altered by abnornal cell division

  • during meiosis
  • by mutagenic agents
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53
Q

Nondisjunction

(genetic problems)

A

failure of homologous chromosomes to sep. properly during

meiosis I

failure of sister chromatids to separate properly during

meiosis II

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54
Q

result of nondisjunction

(genetic problems)

A

3 copies of a chromosome - trisomy

(somatic cells - 2N + 1)

1 copy of chromosome - monosomy

(somatic cells - 2N - 1)

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55
Q

most monosomies and trisomies result in

A

spontaneous abortion of embryo early in term

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56
Q

nondisjunction may also occur in sex chromosomes, resulting in

A

extra or missing copies of X and/or Y

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57
Q

Chromosomal Breakage

(genetic problems)

A

occur spontaneously

or induced by environmental factors

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58
Q

environmental factors causing chromosomal breakage

A

X-rays, mutagenic agents

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59
Q

deficiency

(chromosomal breakage - genetic problems)

A

chromosome that loses fragment

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60
Q

Mutations

definition

(genetic problems)

A

changes in genetic information of a cell

coded in DNA

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61
Q

Mutations in somatic cells

A

can lead to tumors

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62
Q

mutations in gametes (sex cells)

A

transmitted to offspring

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63
Q

most mutations occur in regions of DNA that

A

do not code for proteins

are silent

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64
Q

silent regions of DNA

A

not expressed in phenotype

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65
Q

mutations that change the sequence of the amino acids in proteins are most often

A

recessive

deleterious

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66
Q

Mutagenic Agents

(mutations)

A

mutagenic agents induce mutations

e.g. cosmic rays

X-rays

UV rays

radioactivity

chemical compounds - colchicine, mustard gas

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67
Q

mutagenic agents are generally

(mutations - genetic problems)

A

carcinogenic

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68
Q

colchicine

(chemical compound - mutagenic agent)

A

inhibits spindle formation

causes polyploidy

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69
Q

polyploidy

A

cells and organisms containing more than two paired (homologous) sets of chromosomes

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70
Q

carcinogenic

A

any substance directly involved in causing cancer

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71
Q

mutation types

(mutations - genetic problems)

A

gene

protein

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72
Q

gene mutation

A

nitrogen bases

added

deleted

subsituted

thus creating different genes

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73
Q

protein mutations

A

incorrect amino acid inserted in polypeptide chain

mutated protein produced

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74
Q

mutation

definition

A

genetic error with wrong/no base on DNA at particular position

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75
Q

examples of genetic disorders

A

phenylketonuria (PKU)

sickle-cell anemia

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76
Q

phenylketonuria (PKU)

definition

A

autosomal recessive

genetic disorder

molecular disease

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77
Q

PKU caused by

A

inability to produce proper enzyme for metabolism of phenylanine

78
Q

result of PKU

A

degradation product (phenypyruvic acid) accumulates

can affect mental development

79
Q

Sickle-cell anemia

definition

A

red blood cells become crescent-shaped because contain defective hemoglobin

80
Q

sickle cell hemoglobin characteristic

A

carries less oxygen

81
Q

sickle cell anemia caused by

A

substitution of valine (GUA or GUG)

for glutamic acid (GAA or GAG)

due to single base pair substitution in gene coding for hemoglobin

82
Q

Molecular Genetics

A

DNA is basis for heredity

self-replication ensures that coded sequence will be passed on to successive generations

83
Q

genes composed of

84
Q

DNA contains

A

information coded in sequence of base pairs

85
Q

DNA provides

A

blueprint for protein synthesis

86
Q

DNA reproduces via

A

self replication

87
Q

DNA’s ability to self-replicate is crucial for

A

cell division —> reproduction

88
Q

mutable

A

DNA is mutable and can be altered

89
Q

Changes in DNA and evolution

A

changes in DNA are stable and can be passed on from gen to gen —> evolution

90
Q

CUT PIE

A

cytosine, uracil, thymine

are

PYrimidines

91
Q

PURe As Gold (Ag)

A

Adenine and Guanine are Purines

92
Q

basic unit of DNA

(structure of DNA)

A

nucleotide

93
Q

composition of nucleotide

A

deoxyribose (sugar)

bonded to:

phosphate group

nitrogenous base

94
Q

two types of nitrogen bases

A

purines

pyrimidines

95
Q

purines in DNA

A

adenine

guanine

96
Q

pyrimidines in DNA

A

Cytosine

Thymine

Uracil

97
Q

backbone of nucleotide

A

phosphate group and sugar (deoxyribose)

98
Q

bases arranged as (on chain)

A

side groups

99
Q

physicality of DNA

A

double-stranded helix

100
Q

composition of double-stranded helix

A

sugar phosphate on outside

base pairs on inside

101
Q

hydrogen bonding in double-stranded helix

A

base pairs are attracted by hydrogen bonds

2 hydrogen bonds between A = T

3 hydrogen bonds between C = G

the more C=G pairs, the tighter the two strands are bound

102
Q

base pairing forms

A

“rungs” on interior of double helix

links two polynucleotide chains together

103
Q

Watson-Crick DNA Model

A

double-standed helix

sugar phosphate backgone

nucleotide base pairs inside

A-T; C-G

base pairs bonded via hydrogen bonding

holds together polynucleotide chains

104
Q

DNA replication

(function of DNA)

A

double-stranded DNA unwinds

separates into two single strands

each strand template for complementary base-pairing

synthesis of two new daughter helices proceeds

105
Q

each new daughter helix contains

(DNA replication)

A

strand from parent helix

newly synthesized complementary strand

106
Q

semiconservative

(DNA replication)

A

in reference to new daughter helices complementary to parent helices

107
Q

daughter helices are identical to

A

each other

parent helix

108
Q

Language of DNA

Genetic Code

(fxn of DNA)

109
Q

language of proteins

genetic code

A

20 amino acids

110
Q

to form amino acids, DNA translated by

111
Q

triplet code

A

amino acid codons

64 different codons coding 20 amino acids

112
Q

base sequence of mRNA translated to

A

codons

series of triplets

113
Q

composition of codons

A

sequence of three consecutive bases

codes for particular amino acids

e.g. GGC - glycine

GUG - valine

114
Q

genetic code is universal!

A

genetic code is universal!

for all organisms

115
Q

codon possibilities

A

64 codons based on triplet code

20 amino acids to code for

redundancy

116
Q

redundant codons

A

64 codons

20 amino acids

codon synonyms

multiple codons code for the same amino acid

each codon codes for only one amino acid

117
Q

degeneracy

or

redundancy

of the genetic code

A

property of 64 codons coding for 20 amino acids

118
Q

AUG

A

start codon

Met (Methionine)

119
Q

stop codons

120
Q

RNA

(molecular genetics)

A

ribonucleic acid

polynucleotide structurally similar to DNA

121
Q

RNA structure

A

similiar to DNA

sugar = ribose

contains uracil (U) instead of thymine (T)

usually single stranded

122
Q

RNA found in

A

nucleus

cytoplasm

123
Q

main types of RNA

A

mRNA

tRNA

rRNA

124
Q

all types of RNA are involved in some aspect of

A

protein synthesis

125
Q

mRNA

messenger RNA

fxn

A

carries complement of a DNA sequence and transports it from nucleus to ribosomes

(ribosomes = sight of protein synthesis)

126
Q

mRNA structure

A

composed of ribonucleotides complimentary to “sense” strand of DNA

“inverted” complmenentary of original master DNA

e.g.

DNA - AAC (valine)

mRNA - UUG

127
Q

monocistronic

A

one mRNA strand codes for one polypeptide

128
Q

tRNA

transfer RNA

found in

A

cytopolasm

129
Q

tRNA

fxn

A

aids in translation of mRNA’s nucleotide code into sequence of amino acids

brings amino acids to ribosomes during protein synthesis

130
Q

tRNA quantity

A

40 known types

at least one type of tRNA for each amino acid

131
Q

rRNA

ribosomoal RNA

A

structural component of ribosomes

132
Q

most abundant RNA

133
Q

site of rRNA synthesis

134
Q

Protein Synthesis

2 events

A

Transcription

Translation

135
Q

Transcription

A

information coded in base sequence of DNA transcribed into strand of mRNA

136
Q

DNA is transcribted into mRNA in the ____

then mRNA ____

A

nucleus

leaves nucleus through nuclear pores

137
Q

Translation

site

(protein synthesis)

138
Q

translation process

A

mRNA codons translated into sequence of amino acids

involves tRNA, ribosomes, mRNA, amino acids, enzymes, other proteins

139
Q

tRNA function

(translation)

A

brings amino acids to ribosomes in correct sequence for polypeptide synthesis

140
Q

in translation, tRNA recognizes

A

both amino acid and mRNA codon

dual function

141
Q

tRNA structure

A

reflects function

one end:

contains anticodon - 3 nucleotide sequence

complimentary to one of the mRNA codons

other end:

site of amino acid attachment

142
Q

aminoacyl-tRNA synthetase

A

has active site that binds to amino acid and corresponding tRNA

forms aminoacyl-tRNA

143
Q

ribosomes

structure

A

two subunits - one large, one small

consits of proteins and rRNA

subunits bind together only during protein synthesis

144
Q

ribosome binding sites

(3)

A
  1. mRNA
  2. P site - tRNA
  3. A site - tRNA
145
Q

p site

tRNA ribosome binding site

A

peptidyl-tRNA binding site

binds to tRNA attached to growing polypeptide chain

146
Q

A site

tRNA

ribosome binding site

A

aminoacyl-tRNA complex binding site

binds to incoming aminoacyl-tRNA complex

147
Q

polypeptide synthesis

stages

A

initiation

elongation

termination

148
Q

initiation

(translation)

A
  1. ribosome binds to mRNA near 5’ end

ribosome scans mRNA until binds to start codon (AUG)

  1. initiator aminoacyl-tRNA complex, methionin-tRNA (anticodon 3’-UAC-5’) base pairs with start codon
149
Q

elongation

(translation)

A
  1. hydrogen bonds form between mRNA codon in A site and its complementary anti-codon on incoming aminoacyl-tRNA complex
  2. peptide bond formed between amino acid attached to tRNA in A site and met attached to tRNA in P site
  3. ribosome carries uncharged tRNA in P site and peptidyl-tRNA in A site
  4. translocation - ribsoome advances 3 nucleotides along mRNA in 5’–>3’
  5. uncharged tRNA in P site expelled and peptidyl-tRNA from A site moves onto P site
  6. ribosome has empty A site ready for entry of aminoacyl-tRNA corresponding to next codon
150
Q

translocation

A

(translation - elongation)

ribsome advances 3 nucleotides along mRNA in 5’–>3’

151
Q

termination

(translation)

A
  1. stop codon arrives in A site
  2. signal ribsoome to terminate translation
  3. DO NOT CODE FOR AMINO ACIDS
  4. frequently, polyribosome formed
152
Q

polyribosome formation

A

(translation - termination)

many ribosomes simultaneously translate a single mRNA molecule forming a polyribosome

occurs during termination

153
Q

protein primary formation following termination

A

upon release from ribosome, protein immediately assumes conformation

conformation determined by primary sequence of amino acids

154
Q

Cytoplasmic Inheritance

(molecular genetics)

A

heredity systems exist outside nucleus

DNA found in chloroplasts, mitochondria etc

cytoplasmic genes interact with nuclear genes —> determine characteristics of organelles

155
Q

plasmids

(cytoplasmic inheritance)

A

cytoplasmic DNA

contain 1+ genes

regulate drug resistance in micro-organisms

156
Q

Bacterial genome

structure and location

(Bacterial genetics)

A

single circular chromosome located in nucleoid

may also contain plasmids

157
Q

plasmids

(bacteria)

A

small circular rings of DNA

contain accessory genes

158
Q

episomes

A

plasmids

capable of intergraiton into bacterial genome

159
Q

replication

(bacterial genetics)

A

begins at unique origin

proceeds in both directions simultaneously

160
Q

Genetic Variance

3 mechanisms

(bacterial genetics)

A

transformation

conjugation

transduction

161
Q

method of bacterial replication

A

binary fission

162
Q

binary fission

A

method of bacteria cells replication

asexual process

163
Q

transformation

(genetic variance - bacterial genetics)

A

foreign chromosome fragment (plasmid) incorporated into bacterial chromosome

via recombination

164
Q

conjugation

genetic variance - bacterial genetics

A

“sexual mating” in bacteria

transfer of genetic material between two bacteria that are temporarily joined

165
Q

conjugation

mechanism

genetic variance

bacterial genetics

A

cytoplasmic conjugation bridge formed between two cells

genetic material transferred from donor male (+) to recipient female (-)

bacteria must contain plasmids - sex factors

166
Q

Sex Factor

F factor

Conjugation

Genetic Variation

Bacterial Genetics

A

present in E. coli

bacteria possessing it - F+

bacteria void - F-

during conjugation bw F+/F-

F+ replicates F factor, donates copy to recipient –> converts to F+

167
Q

Sex Factor and transfer

Conjugation

Genetic Variance

Bacterial Genetics

A

genes that code for various characteristics

e.g. antibody resistance

may be found on plasmids and transferred to recipient cells along with sex factors (i.e. F+)

168
Q

Consequences of Conjugation + Sex factors

A

sex factor may become integrated into bacterial genome

during - entire bacterial chromosome replicates and begins to move from donor cell to recipient cell

conjugation bridge breaks before entire chromosome transferred

bacterial genes may recombine with bacteria genes already present to form novel genetic combinations

170
Q

Hfr cells

A

bacterium with a conjugative plasmid (often the F-factor) integrated into its genomic DNA

171
Q

Transduction

(genetic variation - bacterial genetics)

A

fragments of bacterial chromosome accidentally become packaged into viral progeny produced during viral infection

virions may infect other bacteria

introduce new genetic arrangements through recombination with the new host cell’s DNA

the closer two genes are to one another on a chromosome the mroe likely they will be to transduce together

172
Q

Recombination

genetic variation - bacterial genetics

A

occurs when linked genes are separated

via breakage and rearrangements of adjacent regions of DNA

when organisms carrying different genes or alleles for the same traits are crossed

173
Q

regulation of gene expression allows prokaryotes to control their

A

metabolism

174
Q

regulation of transcription is based on accessiblity of

A

RNA polymerase

175
Q

RNA polymerase

A

enzyme

3’ —>

necessary for constructing RNA chains using DNA genes as templates (transcription)

176
Q

gene regulation enables…

(bacterial genetics)

A

prokaryotes to control metabolism

177
Q

another word for gene expression

(bacterial genetics)

A

transcription

178
Q

regulation of transcription based on..

(bacterial genetics)

A

accessbility of RNA polymerase to the genes being transcribed

179
Q

regulation of transcription directed by..

(bacterial genetics)

180
Q

operon

(bacterial genetics)

A

consists of

structural genes

operator gene

promoter gene

181
Q

structural genes

A

sequences of DNA that code for proteins

182
Q

operator gene

A

sequence of nontranscribable DNA

repressor binding site

183
Q

repressor

A

DNA-binding protein

regulates the expression of one or more genes

binds to the operator and blocks the attachment of RNA polymerase to the promoter

preventing transcription of the genes

184
Q

promoter

A

noncoding sequence

intial binding site for RNA polymerase

185
Q

regulator gene

A

codes for synthesis of a repressor molecule

186
Q

in order to transcribe structural genes, RNA polymerase must

A

move past operator

187
Q

regulatory systems function

A

prevent or permit RNA polymerase to pass on to structural genes

188
Q

modes of regulation

A

inducible systems

repressible systems

189
Q

inducible system

basic

(transcription - bacterial genetics)

A

require presence of inducer

190
Q

repressible system

basic

(transcription - bacterial genetics)

A

in constant state of transcription

unless corepressor inhibits

191
Q

inducible systems

mechanism

A

repressor binds to operator

forms barrier that prevents RNA polymerase from transcribing structural genes

Biology (19 decks)

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