Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Biology in Society > Exam 4 > Flashcards

Exam 4 Flashcards

(113 cards)

Start Studying
1
Q

DNA was first (1869) isolated by Swiss chemist

A

Friedrich Meischer; called it “nuclein”.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

(1929) Phoebus Levene discovered

A

deoxyribose as sugar component of DNA.
Discovered four nitrogenous bases of DNA: thymine, adenine, guanine, and cytosine.
Tetranucleotide hypothesis: DNA consisted of short chains of 4 repeating nucleotide units.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

(1928-1943) Several investigators reported experimental results suggesting that DNA carried

A

heritable information

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Nucleic acids are polymers of

A

nucleotides

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

nucleotides are consisted of

A

pentose sugar
- ribose in RNA
- deoxyribose in DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

nitrogenous base consists of

A

purines and pyrimidines.
Purines: G, A
Pyrimidines: C, T (DNA), U (RNA)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Phosphate group consists of

A

Nucleoside: nitrogenous base + sugar.
Nucleotide: nucleoside + ≥ 1 phosphate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Chargaff and Base Composition of DNA

A

analyzed base composition of DNA from several different species
base comparison varies between species
- suggests molecular diversity
regularity in the ratio of nucleotide bases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Chargaff’s Rules

A

Rule 1: Base composition of DNA varies btw species.
Rule 2: %A ≈ %T; %G ≈ %C.
- Use to calculate unknown %s.
Exception: фX174 = bacteriophage
- Has single stranded, circular genome.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Rosalind Franklin (7/25/1920 – 4/16/1958)

A

British biophysicist working in X-ray crystallography.
- ↑ understanding molecular structure of DNA, RNA, viruses.
Data was critical to Watson-Crick DNA model.
- Shown to Watson w/o her knowledge.
- Prepared papers recognizing two forms A and B-DNA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Franklin’s X-ray Crystallography Data

A

X-rays are deflected as pass through DNA fibers.
Watson and Crick assembled models conforming to Franklin’s data and Chargaff’s rules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Watson-Crick Model of Double Helix

A

Duplex DNA: structure consists of two strands.
Two strands are anti-parallel:

Followed Franklin’s conclusion: sugar-phosphate backbone was outside.
- Places hydrophobic bases interior.
Helix makes a full turn every 3.4 nm and bases are stacked 0.34 nm apart.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Nucleic Acids are Directional

A

Phosphodiester bonds result in a polymer w/ distinct ends.
5’ end: ends in terminal phosphate.
3’ end: ends in pentose sugar with free 3’ hydroxyl group.

Covalently linked sugars and phosphates make up phosphodiester backbone.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

________ - ________ only pairing that fits.

A

Purine-pyrimidine
Strands stabilized by hydrogen bonds.
Explains Chargaff’s Rules
Dictates combos btw strands
No sequence restrictions along strand

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Watson-Crick base pairing is key to information sharing in

A

DNA replication
Transcription (DNA > RNA)
Translation (mRNA > polypeptide [protein])

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Leading strand

A

synthesized continuously in direction of replication fork.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Lagging strand

A

synthesized discontinuously in direction away from replication fork

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Helicase

A

uses ATP hydrolysis to unwind DNA duplex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Primase

A

Synthesizes a short RNA primer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

DNA polymerase

A

DNA-dependent synthesis of comple-mentary DNA molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

DNA ligase

A

joins adjacent replicated strands.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Enzymes that catalyze synthesis of new DNA by adding _________ to a preexisting chain.

A

nucleotides
Require primer and a template strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

E. coli

A

several DNA polymerases; two most important for DNA replication
DNA Pol I: removes RNA primer and replaces w/ DNA.
- DNA Pol III: adds DNA nucleotide to RNA primer and continues to add Nts complementary to template strand.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Rate of elongation

A

≈ 500 Nt/sec in bacteria and ≈ 50 Nt/sec in human cells.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
DNA polymerase
catalyzes addition of a nucleotide to the 3’ end of a growing chain
26
Each nucleotide added is in the form of dNTP
dNTP - each monomer is added, pyrophosphate is lost. - Hydrolysis of pyrophosphate is a coupled exergonic rxn.
27
Structural differences RNA vs. DNA
Sugar = ribose (2’ OH) Uracil (U) instead of thymine (T). Usually single stranded
28
Messenger RNA
mRNA: carries information from DNA to ribosome
29
Transfer RNA
tRNA: delivers specific amino acids to ribosome
30
Ribosomal RNA
rRNA: structural and catalytic part of ribosome.
31
Regulatory RNA
regulate gene expression; include microRNA (miRNA), long, non-coding RNA (lncRNA), small interfering RNA (siRNA).
32
intramolecular base pairings of purines and pyrimidines A=U G=C creates intramolecular regions with different structures;
stem: complementary base pairing by antiparallel turns of RNA strand. loop: unpaired region
33
(Francois Jacob and Jacques Monod, 1961) hypothesized that single-stranded RNA
messenger RNA carries info from DNA to ribosomes.
34
Gene Expression in Bacteria
Most genes are continuous. Some genes are organized into operons. - Produce a polycistronic mRNA. Lack of compartment-alization allows coupling of transcription and translation
35
Template strand
used to direct transcription; complementary and antiparallel to RNA. - Also called antisense strand.
36
Non-template strand
NOT usually transcribed; same sequence and polarity as RNA - contains U instead of T. - also called sense = coding strand.
37
Promoter
DNA sequence immediately upstream (5’) of transcription start site (tss); - Not transcribed; controls binding of RNA polymerase
38
RNA coding region:
portion of gene transcribed into mRNA
39
Termination region
sequences located 3’ to coding region; signals end of transcription
40
A single promoter controls the expression of 3 genes
lacZ, lacY, and lacA Products of lacZ and lacY genes involved in lactose metabolism
41
3 clustered genes are coordinately expressed in single mRNA
polycistronic mRNA
42
uncoupled
Nuclear envelope separates trans-cription and translation - transcription = nuclear. - mRNA is transported to cytoplasm for translation.
43
RNA splicing
introns are removed from pre-mRNA
44
5’ cap
addition of a modified guanine to 5’ end of mRNA. - added after ≈ 20-40 Nts are transcribed.
45
poly-A tail
addition of 50-250 adenine residues of 3’ end of pre-mRNA. Functions: - Prevent degradation - Help mRNA transport - Help position mRNA on ribosome
46
Primary transcript is processed to mature mRNA.
introns: regions of gene that are transcribed, but not included in mature RNA. exons: regions of transcribed RNA retained in mature RNA. Exons included translated and untranslated regions.
47
RNA Splicing
Pre-mRNA strand includes exons and introns. RNA splicing: removal of introns and joining of exons to produce mature mRNA
48
Most contain RNA coding regions and noncoding regions
- Exons: RNA coding regions. - Introns: non-RNA coding regions. EX: Ovalbumin gene ≈ 7,700 bp 8 exons, 7 introns; Mature mRNA 1,872 bases
49
Transfer RNA = tRNA
delivers specific amino acids to ribosome. - Specific interactions w/ codon of mRNA.
50
Ribosomes
complex of proteins and rRNA that serve as platforms for translation. - Orient mRNA. - Position tRNAs - Catalyze addition of amino acid to growing polypeptide chain.
51
Character
: a heritable feature that varies among individual. - EX: flower color.
52
Trait
each variant for a character; - EX: purple vs white flowers
53
Gregor Mendel (1822-1884)
Austrian monk who worked out principles of transmission genetics (simple inheritance). Proposed the first theory about the units of inheritance (genes). - Law of segregation - Law of independent assortment
54
Hypothesis of Blended Inheritance
hereditary determinants carried by gametes blend as gametes fuse in fertilization - Blended determinants would produce intermediate traits. - Parental trait should not reappear if blended
55
Hypothesis of Particulate Inheritance
determinants of inheritance are physically distinct. - Remain intact when gametes fuse
56
True breeding
gives rise to plants w/same traits over successive generations
57
Cross-pollination
directed mating technique to ensure parentage of each generation of peas. - reciprocal cross: switch parents contributing trait.
58
The Parental generation is the
P generation
59
the first filial generation is the
F1 Generation
60
Alternative versions of genes account for variations in inherited characters are called;
alleles an organism inherits two alleles, one from each parent
61
If two alleles at a locus differ, then the ___________ _______ determines the organism’s appearance.
dominant allele
62
Law of segregation
the two alleles for a heritable character segregate during gamete formation and end up in different gametes.
63
Monohybrid cross
cross between individuals who are heterozygous for a character.
64
P generation
true-breeding = identical alleles. Gametes produced by one parent will contain same allele.
65
F1 generation
union of parental gametes produces F1 hybrids (Pp) When hybrids produce gametes, the two alleles segregate.
66
F2 generation
Random combination of gametes in F1 x F1 cross result in 3:1 ratio observed by Mendel.
67
Genotype (two types)
combination of alleles ≥ 1 gene of an organism. homozygous: pair of identical alleles heterozygous: 2 different alleles
68
Phenotype (two types of traits)
one or more of an organism’s observable traits. Dominant trait: expressed in F1 organism Recessive trait: masked in F1 but reappears F2 generation.
69
complete dominance
when true-breeding parents carry different traits then, F1 genotypic proportions: all Rr F1 phenotypic proportions: all express dominant phenotype. - F2 genotypic proportions: ¼ RR, 2/4 R/r, ¼ rr. - F2 phenotypic proportions: ¾ dominant, ¼ recessive.
70
transmission of genetic traits is determined by the _______ on homologous chromosomes
alleles
71
Alleles of a gene reside at the same position =
locus on homologous chromosomes
72
Dependent assortment
: two characters assort as a package during gamete formation. Parental combinations of alleles stay together.
73
Independent assortment
two characters assort independently during gamete formation. - Nonparental combinations of alleles can occur.
74
Dihybrid cross
obtain characteristic 9/16, 3/16/, 3/16, 1/16 phenotypic proportions
75
Multiplication rule
probability of ≥ 2 independent events occurring together is product of their individual probabilities. - P(2H,2 tosses) = (1/2)(1/2) = 1/4 (Practice Slide 27 G&H)
76
Addition rule
probability of any one of ≥ 2 mutually exclusive events is sum of their individual probabilities. - P(F2 = heterozygous) = ¼ +1/4) = ½ - Two ways to achieve outcome. (Practice Slide 27 G&H)
77
lack of compartment allows
coupling of transcription and translation
78
F1 phenotype is __________ phenotype of parents.
intermediate
79
Heterozygote
phenotypes of both alleles are measurable
80
ABO blood typing
3 alleles Exhibit both complete dominance and codominance. IA vs. IB = codominant IA, IB vs. i = complete dominance Use to determine transfusion compatibility.
81
Autosomal
located on chromosomes 1-22.
82
Sex chromosome
: located on X or Y.
83
In pictorial representation of family history a horizontal line represents:
mating
84
In pictorial representation of family history a vertical line represents:
connects parents to children
85
In pictorial representation of family history a shading line represents:
indicates whether a person is affected with the trait
86
penetrance
proportion of individuals w/ a genotype that express corresponding phenotype; - trait due to acquisition of new mutation.
87
Incidence of some autosomal dominant disorders is high: Familial hypercholesterolemia Myotonic dystrophy Huntington’s Disease
: ≈ 1/500 in families of European or Japanese descent. ≈ 1/550 in regions of northeastern Quebec vs. 1/8000 worldwide : ≈ 5.7/1x105 if European, N. American, or Australian descent; ≈ 4/1 x 106 if Asian descent.
88
Carrier
individual w/ heterozygous genotype, who is unaffected, but can pass on disease causing allele.
89
Co-sanguinity
: mating btw closely related people. - Increases probability mating between two heterozygotes. - ≈ 1/4 offspring will be affected
90
Genotypes for XX Genotypes for XY
inherit two alleles; homozygous dominant, heterozygous, homozygous recessive. only one allele for each gene = hemizygous Not the same as gender: sex characteristics that are socially constructed.
91
Congenital Generalized Hypertrichosis (CGH)
X-linked dominant disorder. Increased number of hair follicles and body hair. - ♂: full body expression; - ♀: asymmetrical; may be present in patches.
92
Regarding a mutation in a gene on the X chromosome causes the phenotype to be expressed in MALES:
hemizygous for the mutation b/c only contain one X chromosome
93
Regarding a mutation in a gene on the X chromosome causes the phenotype to be expressed in FEMALES:
homozygous for the mutation (copy on each of their 2 X chromosomes).
94
DNA > RNA (mRNA) >
protein
95
a site
aminoacyl- holds an tRNA carrying the next amino acid to be added s
96
p site
peptidyl- hold tRNA with the growing polypeptide attached
97
e site
site from which discharged tRNA will exit
98
triplet code
smallest units possible to code for 20 biological amino acids (4)(4)(4) = 64 possible combinations
99
information flow from DNA to protein is written in a non-overlapping genetic code DNA: mRNA: Protein:
DNA: instructions for protein written as series non-overlapping nucleotides mRNA: series of non-overlapping 3 nucleotide "words" = codons Protein: each codon interacts with tRNA to specify amino acids
100
lack of ambiguity
no codon specifies > 1 amino acid
101
redundancy
some codons are synonyms; specify the same amino acid
102
reading frame
translational machinery reads as series of non=overlapping 3 letter words = codon
103
nearly universal
conserved from bacteria to plants and humans - allows genes to be transplanted from one species to another >>>gene transcribed and translated in cells of second species
104
implication
near universality indicates "language" present early in life - shared by common ancestor
105
melanocortin
hormone influencing deposit of dark pigment in fur mice with dark fur GCG > CGC > Arg mice with light fur ACG > UGC > Cys
106
nucleic acid is
DNA or RNA
107
covered in a protein coat
capsid
108
covered in a coat of membrane
envelope
109
lytic cycle
after making many copies of phage, cell breaks open to release particles - phage injects DNA, which circularizes - phage DNA and proteins are synthesized - phage particles assemble - cell lyses to release phages
110
isogenic cycle
viral DNA inserts into bacterial chromosome and DNA replication occurs without death of bacterium
111
papaya ringspot potyvirus
spread of aphids wiped out native papaya in certain parts of Hawaii reintroduction of genetically engineered PRSV-resistant papaya plants allowed reintroduction
112
3 types of COVID tests approved by FDA
rapid antigen tests: nasal swab, immunoassay, antibodies are the detection method molecular tests: antibody (serology) test: blood sample to detect circulating antibodies, detect with color change
113

Biology in Society (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions