1
Q
gene (def.)
A
coded information in the form of hereditary units inherited from parents to offspring ( segments of DNA sequences that collectively control gene transcription)
2
Q
what is the differences in the chromosome structure between sexually reproducing animals and bacteria.
A
(1) animals = diploid vs bacteria haploid
(2) animals linear chromosome vs bacteria single circular chromosome
(3) animal nucleus vs bacteria plasmid
3
Q
where else do plants and animals have DNA
A
(1) nucleus
(2) mitochondria
(3) chloroplast ( plants)
4
Q
mitosis end result
A
2 genetically identical daughter cells
5
Q
meiosis II end result
A
4 genetically different daughter cells
23 chromosomes (in humans), and each chromosome has only one chromatid — forming four haploid gametes with single copies of each chromosome.
6
Q
genotype vs phenotype
A
genotype = genetic make up
phenotype = visible physical traits
7
Q
what is the central dogma
A
DNA ( double stranded) –> RNA ( single stranded) –> Protein
8
Q
why does the double helix suggest about DNA replication
A
suggests that DNA replication is semi-conservative w/ complementary base pairing
9
Q
purpose of gel electrophoresis
A
separate, identify, and analyze biomolecules such as DNA, RNA, or proteins based on their size and charge.
10
Q
in gel electrophoresis what represents the longer DNA strand the top or bottom
A
top as longer DNA strands travel shorter distances
11
Q
3 components of DNA nucleotide
A
(1) Sugar
(2) phosphate
(3) nitrogenous base
12
Q
How many hydrogen bonds A-T
A
2 H-bonds
13
Q
how many hydrogen bonds G-C
A
3 H-bonds
14
Q
semiconservative replication (def.)
A
each daughter duplex contains one original parental strand of DNA
15
Q
conservative replication (def.)
A
- daughter duplex contains two strand of parental molecule & the other contains two newly synthesized
- “copied as a whole”
16
Q
dispersive replication ( def.)
A
daughter duplex is composed of interspersed parental duplex segments
looks smth like this:
( ——parental —– new – — P— —- — N)
17
Q
3 steps of PCR reaction
A
(1) denaturation: requires template DNA heated to 95 to break hydrogen bonds btwn strands double stranded DNA
(2) primer annealing: temp reduced 48-68 to allow short DNA primers to stick onto DNA strand, requires primers b/c DNA polymerase cannot start from scratch
(3) primer extension: heated to 72 uses TAG polymerase to start adding nucleotides to 3’ end building complementary
(…) sanger sequencing similar but when done ddNTP attach to stop chain growth
18
Q
dideoxynucleotide triphosphate (def.)
A
- missing a 3’OH group on the sugar & 2’ OH which without DNA polymerase cannot add another nucleotide so chain growth stops
19
Q
Next generation sequencing (def.)
A
sequencing by synthesis, cheaper and more time efficient,”massively parallel”
20
Q
3 structural/chemical differences btwn RNA and DNA
A
(1) Double stranded DNA vs single stranded RNA
(2) Deoxyribose sugar DNA vs Ribose sugar
(3) Thymine DNA vs Uracil RNA
21
Q
(messenger) mRNA (def.)
A
- carries the genetic code from DNA and is translated into protiens
- encodes the sequence of amino acids in a polypeptide (single in eukaryotes & 2+ in bacteria)
- short lived, only form of RNA that undergoes translation
22
Q
(transfer) tRNA (def.)
A
adapter molecule carries amino acids to ribosomes for the construction of protiens & binds there to mRNA codons by complementary base pairing to elongate the polypeptide
23
Q
(ribosomal) rRNA (def.)
A
- structural and catalytic component of ribosomes.
- combines w/ proteins to form the large and small ribosomal subunits
- catalyzes peptide bond formation during protein synthesis.
24
Q
transcription in prokaryotes vs eukaryotes
A
(1) prokaryotes: Transcription and translation both happen in the cytoplasm (no nucleus). VS eukaryotes: Transcription occurs in the nucleus, translation in the cytoplasm.
(2) Prokaryotes: mRNA is used immediately VS eukaryotes: Pre-mRNA undergoes processing: 5’ capping, splicing (removal of introns), and 3’ polyadenylation before becoming mature mRNA.
(3) Prokaryotes: Single RNA polymerase synthesizes all types of RNA VS eukaryotes: Multiple RNA polymerases (I, II, III) each synthesize different types of RNA; RNA polymerase II synthesizes mRNA.
25
Which RNA polymerase makes mRNAs in eukaryotes?
RNA polymerase II
26
What is the role of a promoter in transcription?
regulate transcription by controlling RNA polymerase's access to the gene
27
consensus sequence (def.)
typical pattern of dna/rna bases found in many similar sites
- eukarotic TATA box
- prokaryotic -35 box & -10 box
28
enhancer (def.)
DNA element that increases transcription when bound by activator proteins.
29
silencer (def.)
DNA element that decreases transcription when bound by repressor proteins.
30
mechanisms eukaryotes use to increase the diversity of their proteins...
(1) Alternative splicing: splicing introns out
(2) Alternative promoters: different promoter regions within the same gene. that using different promoters causes transcription to start at different sites, generating mRNAs with varied 5′ untranslated regions (UTRs) and sometimes different protein products.
(3) Alternative polyadenylation involves using different poly(A) signal sites in the pre-mRNA. this changes the 3′ end of the mRNA transcript, resulting in mRNAs that vary in length and sometimes in regulatory sequences, affecting mRNA stability and translation.
31
amino acid (def.)
building blocks of polypeptides, made up of a central carbon molecule (alpha carbon), carboxyl group, side chain R group
32
peptide bond (def.)
covalent bond that forms between the carboxyl group (-COOH) of one amino acid and the amino group (-NH₂) of another amino acid during protein synthesis.
33
polypeptide (def.)
def: A polypeptide is a linear chain of amino acids linked together by peptide bonds.
primary structure: sequence of amino acids (peptide bond)
secondary: alpha helix & B pleated sheets ( H-bond)
tertiary: overall 3d shape ( bonds btwn R grps & peptide backbone)
quaternary: combination of polypeptides ( bonds btwn diff polypeptides)
34
which direction is an mRNA translated?
5' - 3'
35
which direction is a polypeptide synthesized
N-terminal w/ free amino group to C-terminal direction that has a free carboxyl group
36
what is UTR
untranslated region which works to regulate RNA strand ensuring...
37
3 phases of translation
(1) initiation: The ribosome assembles at the start codon on the mRNA, and the initiator tRNA carrying methionine binds to it.
(2) elongation: tRNAs bring amino acids to the ribosome, which links them together into a growing polypeptide chain.
(3) termination: When the ribosome reaches a stop codon, the polypeptide is released and the ribosome disassembles.
38
Where does translation happen in a bacteria vs eukaryote
bacteria: translation occurs in the cytoplasm simultaneously w/ transcription VS eukaryotes: occurs in the cytoplasm after transcription is complete in the nucleus
39
polycistronic mRNA (def.)
single mRNA molecule that carries the coding sequences for multiple different proteins, usually found in prokaryotes.
40
why is genetic code in triples
provides the necessary variety and redundancy for the genetic code.
41
synonymous codons (def.)
codons that specify the same amino acids (will have either the two purines or the two pyrimidines)
42
third-base wobble (def.)
mechanism that relaxes the requirement for complementary base pairing btwn the third base of a codon and the corresponding nucleotide of its anticodon
43
aminoacyl-tRNA synthetases (def.) and how its used to translate genetic code
- enzymes that attach the correct amino acid to its corresponding tRNA, creating a charged (aminoacylated) tRNA ready for translation.
- catalyzes the formation of a high-energy bond between the amino acid and the tRNA’s 3′ end.
44
point mutation (def.)
confined to a specific base pair or location in a gene ( add, delete, or substitute)
45
silent mutation
specifies the same amino acid
46
missense mutation
amino acid change to the protein
47
nonsense mutation
creates a stop codon in place of amino acid
48
frameshift mutation
insertion/deletion of +1 base pair altering the reading frame changes every amino acid after
49
regulatory mutation.
doesnt affect transcript occur in noncoding region ( promoters, introns, UTR)
50
forward mutation
converts wild type to a mutant allele
51
reverse mutation
- true reversion
- intragenic reversion
- second site reversion
convert a mutant to wild type
true = DNA sequence reverts to encoding OG message
Intragenic = second mutation happens somewhere else in same gene restores normal function
second site: mutation in a diff gene compensates for the original mutation
52
are centromeres always in the center of the chromosome
NO!
53
chromatin(def)
complex of DNA and proteins (mainly histones) found in the nucleus of eukaryotic cells that packages and organizes DNA into a compact, manageable form
54
euchromatin (def.)
regions of lesser chromatin compaction, this have actively transcribed genes
55
heterochromatin (def.)
facultative vs constitutive
regions of higher chromatin compaction, more likely to contain repetitive DNA sequences that may be located in multiple regions of the genome
Constitutive: always densely compacted
Facultative: levels of compaction very
56
position effect variegation (PEV)
- suggests a direct link btwn gene transcription & level of DNA compaction
- phenomenon where a gene’s expression is variably silenced depending on its position near heterochromatin due to a chromosomal rearrangement.
56
what is beads on a string
the appearance of chromatin under an electron microscope, where DNA is wrapped around histone proteins forming nucleosomes that look like beads on a thin DNA strand (the string).
57
open promotor vs closed promotor
Open promoter = gene can be transcribed
Closed promoter = gene is silenced or off
58
open chromatin vs closed chromatin
Open chromatin = active genes
Closed chromatin = silent genes
59
DNase I hypersensitive
region of DNA that is especially accessible to the enzyme DNase I, indicating that the chromatin in that area is open and transcriptionally active or regulatory
60
epigenetic
heritable changes in gene expression that do not involve changes to the DNA sequence itself, but instead are caused by chemical modifications to DNA or chromatin.
61
primary modifications to histones
Acetylation:
Histone acetylation adds acetyl groups to lysines, loosening DNA-histone interactions and promoting gene expression.
Methylation:
Histone methylation adds methyl groups to lysines or arginines, which can either activate or repress gene expression depending on the site.
62
nucleotide methylation
the addition of a methyl group to a nucleotide base most commonly to cytosine which can affect gene expression without changing the DNA sequence.
63
allele
variant form of a gene found at a specific position (locus) on a chromosome.
64
haploid
single copy
65
diploid
two copies
66
gamete
a sex cell (sperm or egg) that carries half the number of chromosomes (haploid) and can fuse with another gamete during fertilization to form a new organism.
67
blending theory (def.) and how mendel challenged it
ex: red x white flower = purple flower
- mendel realized after crossing parental homozygous generation producing heterozygous F1 that theory was false
68
5 critical experimental innovations Mendel used
(1) controlled genetic crosses btwn plants
(2) use of pure bleeding strains to begin the experimental controlled crosses
(3) selection of dichotomous traits
(4) quantification of results
(5) use of replicate, reciprocal, and test crosses
69
dominant (def.)
expresses its trait even if only one copy is present in the organism (heterozygous condition).
70
recessive (def.)
version of a gene whose trait is only expressed when two copies are present (homozygous recessive) and is masked by a dominant allele if one is present.
71
law of segregation (def.)
The two alleles for each trait will separate (segregate) from one another during gamete formation, and each allele will have an equal probability of inclusion in a gamete. Random union of gametes at fertilization will unite one gamete from each parent to produce progeny in ratios that are determined by chance
72
law of independent assortment (def.)
alleles for different traits assort independently during gamete formation. This means the F1 plants produce four types of gametes: RG, Rg, rG, and rg, each with a probability of 1/4.
73
p-value (def.)
less than 0.05 the diff btwn observed and expected results is statistically significant & experimental hypothesis is rejected; if greater non significant deviation = failure to reject
74
autosomal recessive
- recessive allele results in a trait only if an individual inherits two copies of that allele one from each parent
- males & females are approximately equal frequency
- often child w/ recessive has parents who both have dominant trait and are heterozygous carriers
- if both parents have the trait (ie homozygous recessive) all children will have
- trait is not seen in every generation, instead seen among siblings
- if it is rare and just one of the parents has the trait a child can only have it if other parent is heterozygous
75
autosomal dominant
- trait must appear both in individuals who have a heterozygous genotype ; and in those with homozygous genotype
- males and females will show the trait in approximately = #
- each person w/ the trait has at least one parent w/ the trait
- parents of either sec can transmit the trait to a child of either sex
- if neither parent had the trait none of their children will have it
- if trait is rare
- person w/ trait likely hetero
- both parents have it, can produce child w/o
76
chromosome vs chromatid vs sister chromatid
Chromosome: A single, long DNA molecule containing many genes; can exist as one or two chromatids depending on the stage of the cell cycle.
Chromatid: One copy of a duplicated chromosome; forms after DNA replication.
Sister chromatids: The two identical chromatids of a duplicated chromosome, joined together at the centromere.
77
How many chromosome are there in G1
diploid number of chromosomes in humans, that’s 46 chromosomes (23 pairs).
78
How many chromosome are there in G2
46 chromosomes, but each chromosome now consists of two sister chromatids (so there are 92 chromatids total).
79
In a diploid cell, how many alleles are there for each gene? Where are they located?
two alleles for each gene — one inherited from the mother and one from the father. located on the same locus (position) of homologous chromosomes.
80
end of meiosis I how many chromosomes
each daughter cell has half the number of chromosomes as the original diploid cell — so in humans, 23 chromosomes (haploid), each still made of two sister chromatids.
81
Summary of each stage in Meiosis
Meiosis I – “reduction division”
- Prophase I: Crossing over; homologs pair
- Metaphase I: Homologs line up
- Anaphase I: Homologs separate
- Telophase I: Two haploid cells form
Meiosis II – “division of sister chromatids”
- Prophase II: New spindles form
- Metaphase II: Chromosomes line up
- Anaphase II: Sister chromatids separate
- Telophase II: Four haploid cells form
82
synapsis (def.)
the pairing of homologous chromosomes during prophase 1 of meiosis
83
synaptonemal complex (def.)
its formation is initiated by the synapses it is a trilayer protein structure that maintains synapsis by binding nonsister chromatids of the homologs close to each other.
84
crossing over (def.)
occurs between nonsister chromatids of homologous chromosomes exchange DNA segments creating genetic recombination --> increases genetic diversity
85
chiasma (def.)
contact point between the nonsister chromatids, which are located along chromosomes where crossing over has occurred
86
how meiosis explained Mendel’s laws of segregation & independent assortment
Law of Segregation: During anaphase I of meiosis homologous chromosomes (and their alleles) separate so each gamete receives only one allele of each gene(separating Aa to A & a in diff cells)
Law of Independent Assortment: During metaphase I of meiosis, homologous chromosome pairs line up randomly, allowing alleles of different genes to assort independently into gametes.
87
hemizygous (def.)
refers to the male genotype for X-linked genes
- Cannot be homozygous or heterozygous for X-linked gene because there is only 1 X chromosome
- Hemizygous males inherit one X chromosome from the mother and express any genes on it
88
chromosomal sex (def.)
specified at fertilization, the presence of sex chromosomes associated with male/female (XX or XY)
89
phenotypic sex ( def.)
- the internal and external morphology found in each sex
- determined by gene expression and the development of sex characteristics
during gestation / growth
90
dosage compensation (def.)
the mechanism for equalizing the expression of X-linked genes in males and females of a species
91
Barr body (def.)
- One-half of the somatic cells contain a Barr body of the maternal chromosome
- other half of the somatic cells contains a Barr body of the paternal chromosome.
92
proband
first generation to exhibit a certain disease
93
X linked dominant
- Females can be homozygous dominant or heterozygous for the gene will express it
- Males homozygous for the gene will express it
94
X linked recessive
- Females must be homozygous for the gene to express the phenotype
- Males who are hemizygous for the gene will express the phenotype
- Causes many more males than females to express the gene
95
Nondisjunction
Failed chromosome separation during anaphase, often results in abnormal # of chromosomes
95
disjunction
process during anaphase of meiosis or mitosis when chromosomes or chromatids separate and move to opposite poles of the cell.
Bio 97 Cinquin/Warrior
flashcards
Decks in class (1)
# Cards
