post midterm stuff Flashcards
1
Q
what is the principle of dominance?
A
In a heterozygote, one allele may conceal the presence of another
2
Q
what is the principle of segregation?
A
in a heterozygote, 2 different alleles segregate during the formation of gametes
3
Q
homozygote
A
the same, diploid individual has 2 copies of the same allele
4
Q
heterozygote
A
different, diploid individual has 2 different alleles of the same gene
5
Q
true breeding
A
breeding where the parents would produce offspring with the same phenotype
6
Q
cross-fertilization
A
fertilize a plant using pollen from another plant of the same series
7
Q
monohybrid
A
mono meaning one, hybrid is the offspring of 2 organisms from different species, ex. TT x tt
8
Q
filial
A
son or daughter
9
Q
ex. of a genotype
A
AA homozygous dominant
10
Q
ex. of a phenotype
A
blue eyes
11
Q
what is the S phase of the cell cycle?
A
DNA replication, making genetic copies of the cell before they divide to ensure each new cell receives the right amount of chromosomes
12
Q
what is transcription?
A
the process of copying a segment of DNA into RNA
13
Q
what is translation?
A
where a genetic code from a strand of mRNA is decoded to produce a particular sequence of amino acids, takes place on ribosomes
14
Q
what is genotype in molecular biology?
A
typically the DNA sequence that codes for an RNA
15
Q
what is a phenotype in molecular biology?
A
typically the action of the corresponding RNA or protein
16
Q
what is the principle of independent assortment?
A
the alleles of different genes segregate or assort independently of one another
17
Q
what biological process explains segregation and independent assortment?
A
meiosis
18
Q
what is incomplete dominance?
A
the phenotype in a heterozygote is a mix or in the middle between the phenotype of the two homozygotes ex. red flower + white flower = pink flower
19
Q
what is codominance?
A
both alleles show phenotypes in a heterozygote ex. white cow + brown cow = white and brown cow
20
Q
ABO glycosyltransferase in the cell becomes what and where?
A
becomes a red blood cell in the bone marrow
21
Q
what is epistasis?
A
an allele of one gene hides the effects of alleles of another gene- homozygous recessive phenotype
of one gene (e) overrides both
dominant (B) and recessive (b)
alleles of the other gene.
22
Q
what is pleiotropy?
A
one gene controls the expression of several phenotypic traits, ex. sickle cell anemia allele causes 2 different phenotypes- sickle cell disease and resistance to malaria
23
Q
why would it be a “bell-shaped curve”?
A
continuous variation in a natural population as opposed to discontinuous variation (having many independent small effects leads to a bell)- also called normal distribution
24
Q
meiosis?
A
each gamete receives only one copy (chromatid) from each homologous pair of chromosomes, as a result gametes are haploid
25
diploid?
having 2 complete sets of chromosomes one from each parent
26
haploid?
having a single set of unpaired chromosomes
27
which structure is not a part of the nucleus?
nucleoid
28
what is it called when a population has more than 2 alleles of a gene?
multiple genes
29
what is polygenic inheritance?
alleles of multiple genes have additive effects on a quantitative trait
30
if the 2 genes are on the same chromosome then why do recombinants appear at all?
genes that are on the same chromosome travel through meiosis together, however alleles of chromosomally linked can be recombined by crossing over
31
how do you get new combinations of previously existing genetic material?
independent assortment of chromosomes in meiosis OR crossing over of homologous chromatids in meiosis
32
what is the site of crossing over called?
chiasma
33
what generates the most recombination?
independent assortment of chromosomes
34
what does the physical distance between alleles on the same chromosome dictate?
it dictates the probability of crossing over happening between 2 loci, a measure of genetic distance between alleles
35
what is synaptonemal complex?
a protein structure that forms between 2 homologous chromosomes in meiosis thought to mediate synapsis and recombination (meiosis 1 in eukaryotes)
36
what is the difference between eukaryotes and prokaryotes?
eukaryotes have a nucleus, mitochondria, and other organelles; prokaryotes have no organelles except ribosomes
37
what are the similarities between eukaryotes and prokaryotes?
both have DNA, cell wall, plasma membrane, and ribosomes
38
what is the maximum frequency of recombinants and why?
50%, independent assortment and any number of crossovers yields 50% recombinant gametes
39
how do you count recombinant and nonrecombinant chromosomes?
a test cross
40
what chromosome do females lack?
Y chromosome
41
in humans what gene determines sex and where is it?
the SRY gene, it is located on the Y chromosome
42
what does the testis-determining factor (TDF) determine?
causes the gonad to develop as a testis instead of an ovary
43
what are the chromosomes and symptoms of Klinefelter syndrome?
male XXY, low testosterone and infertile
44
what are the chromosomes and symptoms of turner syndrome?
female XO, missing X chromosome, short neck, wide chest,
45
are most people with red-green color blindness male or female, why?
male, because they only have 1 X chromosome so if it is passed down they will be affected
46
what are pedigrees used for?
to determine dominant and recessive traits in human families, assess the probability of receiving those traits
47
what is hemophilia?
uncontrolled bleeding due to a defect in one of the proteins needed for blood clotting
48
what is chromatin made of?
nucleic acid + proteins
49
what is a bacteriophage?
a virus that infects bacteria
50
what element is found in DNA and not protein?
phosphorous
51
what element is found in protein but not DNA?
sulfur
52
in the covalent structure of DNA what are the bases called?
purine (AG) and pyrimidines (CT)
53
what are the 3 hypothetical DNA replication mechanisms?
semi-conservative, conservative, and dispersive
54
what does topoisomerase do during DNA replication?
prevents twisting as DNA unwinds and rejoins the DNA strands
55
how does the cell prevent 2 separated strands from snapping back together again?
the complementary base pairs zipper the 2 strands together by hydrogen bonding
56
what do single-stranded binding proteins do in DNA replication?
they coat each separated strand, preventing them from coming back together
57
what does a cell need to do in order to make a copy of its DNA?
that primase adds nucleo8des to the RNA primer at the 3ʹ′
end. Once the primer is completed, primase detaches, and a
DNA synthesizing enzyme, DNA polymerase III, a
57
what does a cell need to do in order to make a copy of its DNA?
the primase adds nucleotide to the RNA primer at the 3' end, when the primer is completed the primase detaches and DNA polymerase III attaches to the exposed 3' end of the RNA primer
58
what does a sliding clamp do?
prevents DNA polymerase from falling off prematurely
59
how does DNA polymerase do once attached to the 3' end of the RNA primer?
it extends the daughter strand by adding complementary DNA nucleotides on the strand in the 5' to 3' direction
60
why does one the RNA primers face the wrong way?
because the 2 DNA strand run in opposite direction (antiparallel)
61
DNA polymerase III synthesizes DNA away from the replication fork producing _______?
producing a short piece of DNA called and Okazaki fragment
62
what does DNA polymerase I do?
extends the Okazaki fragment, removing ribonucleotides of the RNA primer and replacing them with deoxyribonucleotides
63
what enzyme is needed to repair the nick left by DNA polymerase I?
DNA ligase
64
what is helicase?
the unzipping enzyme in DNA replication
65
what do DNA polymerase need to replicate DNA?
dNTPs, a primer nucleic acid with free 3'-OH, template DNA to specify the sequence of a new strand
66
where is the replication origin (single) for small circular chromosomes?
most prokaryotes, mitochondria, chloroplasts
67
where is the replication origin (multiple) for linear and large chromosomes?
nuclear genomes of practically all eukaryotes
68
how do genes produce the traits we observe in an organism's phenotype?
DNA codes for RNA - transcription
RNA codes for proteins - translation
proteins (don't code for DNA or RNA) the activity of the RNA and proteins produce observed phenotypes
69
what is gene expression?
the process when the nucleotide sequence of a gene directs protein synthesis to produce the structures of the cell
70
where does transcription occur in prokaryotes?
cytoplasm
71
where does transcription occur in eukaryotes?
nucleus
72
transcription of a gene occurs in what 3 stages?
initiation, elongation, and termination
73
in the initiation of transcription, a gene consists of what?
a promoter and a transcription unit
74
the combination of what forms the transcription initiation complex?
the combination of transcription factors and RNA ploymerase
75
in prokaryotes how do transcription and translation happen together?
mRNAs are translated by ribosomes, while the mRNAs are still being transcribed by RNA polymerase
76
eukaryote mRNAs must go through processing in the nucleus before they are ready to leave the nucleus, what is the mRNA called before and after processing?
the initial mRNA is called a PREcursor mRNA and after processing the mRNAs are called mature mRNAs
77
what is the guanine cap used for in mRNA processing in eukaryotes?
a guanine cap is added to the 5' end of a pre-mRNA by a capping enzyme while the mRNA is still be transcribed by the nucleus
78
what are the 3 things a guanine cap does?
1) protects mRNAs from degradation by RNA exonucleases once the mRNAs enter the cytosol
2) facilitates the transport of mRNAs from the nucleus out through the nuclear pores, into the cytosol
3)the site where ribosomes attach to the mRNA a the beginning of the translation in the cytosol
79
once the pre-mRNA is fully transcribed what does poly(A) polymerase add?
the enzyme adds a chain of 50-250 adenine nucleotides one at a time to the 3' end of each pre-mRNA
80
what is the poly (A) tail important for?
1) nuclear export
2) facilitating transportation
3) the length of the tail can determine how many times an mRNA is translated before it is enzymatically degraded in the cytosol by the RNA exonucleases
81
how are introns removed from pre-mRNAs?
introns are spliced out of the mRNA and the exons are connected together (introns are excluded from mature-mRNAs)
82
what is messenger RNA - mRNA?
a long polynucleotide strand possessing the code for a particular polypeptide chain on it
83
what is a codon?
it is 3 nucleotide bases in length and most codons code for a particular amino acid that is to be added to a polypeptide chain
84
what is transfer RNA (tRNA)?
adaptors to match amino acids to mRNA sequences. they have a covalently attached amino acid and a corresponding anticodon
85
what is ribosomal RNA (rRNA)?
part of the structure of the ribosome, the factory that makes proteins
86
what does the start codon (AUG) do?
starts translation and also codes for the amino acid methionine
87
what do stop codons do?
they stop translation, they do not code for any amino acid
88
why is the genetic code said to be degenerate?
18 of the amino acids are coded for by more than one codon
89
why is the genetic code said to be universal?
almost all living things use an identical genetic code
90
what is the adaptor hypothesis?
adaptor molecules linked to amino acids contain an anti-codon that can base pair with mRNA
91
what is an aminoacyl-‐tRNA synthetase?
an enzyme in the cytosol that adds the correct amino acid to the tRNA with the appropriate anticodon
92
in eukaryotes, ribosomal subunits are made from what and where?
made from rRNAs and proteins in the nucleolus of the nucleus, then they leave the nucleus and become functional in the cytoplasm
93
some polypeptides form a functional protein by themselves, what can be said about the genes?
just one gene has to be expressed to produce these proteins
94
some polypeptides are joined with other different polypeptides in order to form a functional protein, what can be said about the genes?
2 or more different genes must be expressed to produce this functional protein
95
What produces the phenotypic expression of the gene?
the functional protein
96
how many genes and polypeptide chains does myoglobin have?
1 polypeptide chain and 1 gene
97
how many polypeptide chains and genes does a hemoglobin have?
4 polypeptide chains and 2 genes
98
what is post-translational modification?
after proteins leave the ribosome they are folded are modified in some way
99
what are the 3 producers of genetic variation?
1) mutations
2) independent assortment
3) recombination
100
what is missense mutation?
a single base substitution can change the meaning of a codon, often alter after protein function, can be neutral
101
what is a frameshift mutation?
an insertion or deletion can disrupt the reading frame
102
what are silent mutations?
usually, neutral mutations that do not have an observable effect on the phenotype
103
what are nonsense mutations?
premature stop codon usually result in inactive or absent protein
104
what is the usual result of a frameshift?
a nonfunctional protein
105
what are the things genes can code for?
enzymes, proteins, and polypeptides, and any kind of RNA
106
what is the main energy currency of the cell?
ATP
107
what is cellular respiration?
a process that cells use to get energy from food molecules usually with oxygen, energy found in ATP
108
what is substrate-level phosphorylation and where does it occur?
where a phosphate group is transferred from a substrate to ADP and occurs in the cytoplasm and mitochondria
109
what is oxidative phosphorylation and where does it occur?
uses the energy released from the electron transport chain to generate ATP, occurs on the inner membrane of the mitochondria
110
what are anabolic pathways?
use energy to build complex molecules from simpler ones ex. photosynthesis and synthesis of macromolecules
111
what are catabolic pathways?
release energy by the breakdown of complex molecules into simple compounds ex. energy extracted from the breakdown of glucose
112
where is glycolysis found?
most bacteria, archaea, and eukaryotes
113
what are the stages of glycolysis?
energy investment, cleavage, energy payoff
114
what happens during energy investment?
2 ATP molecules are used to phosphorylate the original glucose making it more reactive
115
what is lactate fermentation?
in animals, pyruvate, when it is reduced, is converted to lactate
116
what is alcoholic fermentation?
in brewing yeast, anaerobic reduction of pyruvate leads to alcohol formation in 2 steps- pyruvate to acetaldehyde then acetaldehyde to ethanol
117
when cells sustain glycolysis by fermentation ATP is only available from what?
substrate-level phosphorylation
118
what is an aerobes lifestyle?
many archaea, bacteria, and eukaryotes need O2 to survive and are unable to live solely by fermentation
119
what is a facultative anaerobes lifestyle?
able to switch between fermentation and anaerobic respiration relying on the availability of O2
120
what is an obligate anaerobes lifestyle?
requires an O2 free environment to survive gaining ATP from fermentation or anaerobic respiration
121
where do heterotrophs get their energy?
from other living things
122
where do autotrophs get their energy?
from abiotic sources ex. the sun
123
what is glycolysis?
breaking glucose into two 3 carbon molecules, in the cytosol, doesn't use oxygen
124
what is cellular respiration?
oxidizing fuels to release energy, which happens in mitochondria or plasma membrane, requires O2 and energy from glucose
125
what is the difference between reduction and oxidation?
reduction is the gain of an electron, oxidation is the loss of an electron
126
what are redox reactions?
the transfer of electrons between molecules or atoms and consists of an oxidation, reduction, and 2 half reactions
127
why is a hydrogen atom often added to the reduced molecule?
to neutralize the charge of the electron received and lost from the oxidized molecule
128
what is the function of the inner-mitochondrial membrane?
electron transfer and ATP synthesis by ATP synthase
129
what is the function of the mitochondrial matrix?
reactions removing electrons from fuel molecules (pyruvate oxidation, citric acid cycle)
130
to enter the Krebs/citric acid cycle what must the pyruvate do?
pyruvate must first be converted to acetyl-CoA
131
pyruvate passes through what to get to the Krebs cycle?
passes through the mitochondrial membranes and then into the matrix before the Krebs cycle
132
how does acetyl-CoA enter the Krebs cycle?
acetyl-CoA is combined with a molecule oxaloacetate to form a molecule of citrate
133
what are respiratory electron transport chains and where are they located?
they are located on the folded inner membrane of the mitochondrion (cristae) they are a series of exergonic redox reactions involving a series of electron acceptor molecules
134
what is chemiosmosis?
the return of H+ to the matrix due to the electric field and difference in concentration
135
what is aerobic respiration?
reactions that transfer energy from O2 and organic nutrients to ATP while releasing waste products CO2 and H2O
136
where does the electron transport chain pump hydrogen ions and what is the result?
pumps them from the matrix into the intermembrane space this results in a separation of charges
137
can a difference in solute concentration be used as a source of energy?
YESSSSS
138
what is photosynthesis?
energy from light, stored as organic carbon compounds and an electron acceptor (almost always O2)
139
what are the 2 criteria used to classify something as a living thing?
their carbon source and their energy source
140
what two ways can organisms obtain carbon?
autotrophs- able to carry out carbon fixation using CO2 as a carbon source "primary producers" and heterotrophs- feed on organic matter produced by other organisms, unable to produce their own carbon compounds
141
what is the difference between phototrophs and chemotrophs?
phototrophs use light as an energy source and chemotrophs use the oxidation of reduced compounds from the environment as an energy source
142
what are some examples of photoautotrophs?
plants, algae, cyanobacteria, various oddball creatures
143
what are the thylakoid membranes called grana for?
they are the green colored membranes that harvest light
144
what are the 2 sets of reactions that photosynthesis consists of?
light reactions- the light-driven production of ATP and NADPH AND carbon fixation- the conversion of CO2 to carbs
145
why are plants green?
chloroplasts absorb the light (blue and red) to use the energy
146
what is a photosystem?
a large complex of proteins and pigments in the chloroplast thylakoid membrane, containing a reaction center and antenna complexes
147
what are antenna complexes?
organized units where chlorophyll molecules in the thylakoid membrane are associated with being chlorophyll-binding proteins
148
where does the antenna complex transfer light energy?
into the reaction center
149
what is the reaction center?
a complex of chlorophyll a molecules and proteins, and the primary electron acceptor
150
what do the antenna complexes do?
they are the main light-harvesting systems, they contain lots of chlorophyll and other pigments like carotenoids. they transfer light energy to the reaction centers of photosystem II and photosystem I
151
what is the function of photosystem II?
splitting of water to get electrons, steals electrons from water making O2 (photolysis)
152
what is the function of photosystem I?
reduces NADP to NADPH
153
what is a similarity between both photosystems?
both are able to feed high energy electrons into electron transport chains
154
what is the purpose of the Calvin cycle?
to make glucose and other organic compounds
155
what is the most abundant enzyme on earth?
rubisco
156
what is mesophyll?
the main photosynthetic cell type in vascular land plants
157
what is the stomata?
pores that can open and close
158
what are the molecules of the 3-phosphoglycerate used for?
most of the molecules are used to continue the Calvin cycle while the rest are available to make glucose
159
how do enzymes catalyze reactions?
they lower the activation energy required
160
what factors can denature an enzyme?
temperature and pH
161
how would a cell transport a fully translated protein through it's plasma membrane?
endocytosis or exocytosis
