final exam Flashcards
1
Q
what are carbohydrates made of?
A
carbon and water
2
Q
are carbohydrates soluble in water?
A
yes, since they are polar (they have oxygen)
3
Q
which macromolecules are polymers?
A
carbohydrates, proteins, nucleic acids
4
Q
are lipids soluble in water?
A
no, since they are nonpolar. Nonpolar molecules don’t mix with polar (water).
5
Q
what are lipids made up of?
A
C and H
6
Q
are proteins soluble in water?
A
some are, some are not. It depends on the type of amino acids and R-groups that make the amino acid.
7
Q
which types of amino acids add reactivity to the protein?
A
charged ones
8
Q
are nucleic acids soluble in water?
A
yes, they are polar molecules
9
Q
what are nucleic acids made of?
A
- a nitrogenous base
- a five carbon ring shaped sugar
- one to three phosphate groups
10
Q
what are the 4 polysaccharides?
A
- chitin and cellulose
- glycogen and starch
11
Q
what is the function of chitin?
A
support and rigidity
12
Q
what is the function of cellulose?
A
support and rigidity
13
Q
what is the function of glycogen?
A
energy storage (in animals)
14
Q
what is the function of starch?
A
energy storage
15
Q
what are the 4 groups of amino acids?
A
- nonpolar
- uncharged polar
- negatively charged polar
- positively charged polar
16
Q
what are uncharged amino acids?
A
uncharged but have oxygen so polar
17
Q
which types of amino acids are polar?
A
uncharged, negative, positive
18
Q
how do amino acids affect the function of the protein?
A
- the type of R-group (soluble or not, polar or not)
- the type of amino acid (soluble or not, polar or not)
- the way they are folded
- different combinations of amino acids
19
Q
what are some similarities between archea and bacteria?
A
- no nucleus
- single chromosome
- no organelles
- ribosomes
20
Q
what are some differences between archea and bacteria?
A
- archea have histones, not bacteria
- bacteria have peptidoglycan, not archea
- archea has multiple RNA polymerase
21
Q
what are some similarities between bacteria and eukarya?
A
ribosomes
22
Q
what are some similarities between archea and eukaryotes?
A
- histones
- multiple RNA polymerase
- ribosomes
23
Q
what are some differences between prokaryotes and eukaryotes?
A
- eukarya has a nucleus
- eukarya has more than 1 chromosome
- eukarya have organelles
24
Q
what are the unique characteristics of eukaryotes?
A
- seperation of DNA and cytoplasm by a nuclear envelope (nucleus)
- presence of organelles (membrane bound compartments with specialized function) in the cytoplasm
25
what are the characteristics of protists?
- mostly unicellular
- nucleus and multiple linear chromosomes
- organelles (mitochondria, chloroplast, microtubules; motility and cytoskeletal support)
26
what are the characteristics of fungi?
- they have a cell wall made of chitin
- they can release enzymes and produce antibacterial compounds
27
what are the characteristics of animals?
- muticellular
- no cell wall
- heterotrophs
- use O to metabolize food
- store excess energy as glycogen
- motile at some point in their lives
- reproduce asexually or sexually
28
what are the characteristics of plants?
- have a cell wall made of cellulose
- produce chlorophyll as a photosynthesic pigment
- store excess sugar as starch
- have 2 multicellular phases
- multicellular
29
how are chromosomes during G1?
unreplicated, 2 pairs of each chromosomes (2n)
30
how are chromosomes during G2?
each chromosome is doubled (2 sister chromatids) (2N)
31
how are the chromosomes during prophase?
they condense into threads that become visible under the microscope. They are still double (2N)
32
how are the chromosomes during prometaphase?
the microtubules attach to kinetichores of each chromosome. (2N)
33
how are the chromosomes during metaphase?
they align at the spindle midpoint (metaphase plate) (2N)
34
how are the chromosomes during anaphase?
- now 92 chromosomes
- now 4n : 4 unreplicated chromosomes
- spindle separate the 2 sister chromatids and move them to opposite spindle poles creating daughter chromosomes
35
how are chromosomes during telophase?
they unfold and return to interphase state (4n)
36
how many chromatids are there per chromosome?
2
37
what does diploid mean?
there are 2 copies of each chromosome (2n)
38
what does haploid mean?
there is one copy of each chromosome (1n)
39
what is mitosis?
a process in which a cell replicates its chromosomes, segregate them, producing 2 identical nuclei in peparation for cell division. It creates another identical cell.
40
what is meiosis?
a process to create gametes (sex cells) - 1n
41
what phases are in interphase?
G1, G2, S phase
42
what is G1 in mitosis?
- unreplicated chromosomes
- organelles grow
- RNA and proteins are synthesized
43
what is S-phase in mitosis?
DNA is replicated
44
what is G2 in mitosis?
-chromosomes are now 2 sister chromatids held together by a centromere
- DNA is checked for mistakes
- centrioles (in centrosome) have doubled in pairs
45
what is prometaphase in mitosis?
-microtubules generated by spindles attach to kinetochores of each chromosome
46
what is metaphase in mitosis?
- chromosomes align on metaphase plate
47
what is anaphase in mitosis?
- spindle seperates the 2 sister chromatids of each chromosome and move them to opposite spindle poles
- centromeres break
- 4 unreplicated chromosomes
48
what is telophase in mitosis?
- chromosomes decondense, unfold, and return to interphase state
- nucleus reforms (2)
- cytoplasm begins to divide
49
what is cytokinesis in mitosis?
cytoplasm cleaves and divides into 2 daughter cells
50
what is the interphase of meiosis?
same as mitosis (2n - 2N)
51
what happens during prophase I in meiosis?
- chromosomes begin to condense (2 sister chromatids per chromosome)
- synapsis: homologous chromosomes come together and pair (4 chromatids within 2 homologous chromosomes - tetrad)
- recombination: chromatids of homologous chromosomes undergo recombination and exchange segments
52
what ensures genetic diversity?
- recombination
- independant assortment of chromosomes in meiosis
53
ploidy prophase 1 meiosis
2N
54
what happens in prometaphase I of meiosis?
same as mitosis (2N)
55
what happens in metaphase I?
- homologous pairs of chromosomes align randomly on metaphase plate = independant assortment
56
ploidy metaphase I
2N
57
what happens in anaphase I?
- seperation of 2 chromosomes of each homologous pair and move to opposite spindle
- no break in centromeres
- poles now contain the haplooid number of chromosomes
58
Ploidy anaphase I
2N
59
what happens in telophase I?
- chromosomes undergo little to no change (don't decondense)
- first spindle disassembles and 2 new ones are created
60
ploidy telophase I
1N (division of cell)
61
what happens after telophase I?
Prophase II
62
what happens in prophase II?
- chromosomes condense and a spindle forms
- no prometaphase since there is no nuclear membrane
63
ploidy prophase II
1N
64
what happens in metaphase II?
chromosomes align on metaphase plate
65
ploidy metaphase II
1N
66
what happens during anaphase II?
- microtubules seperate chromatids of each chromosome and go to opposite poles (2n)
67
ploidy anaphase II
2n
68
what happens in telophase II?
- chromosomes decondense
- new nuclear envelope
69
ploidy telophase II
4 times 1n cells
70
what is the effect of genetic recombination on chromosomes?
genetic recombination causes bits of genetic info to be exchanged to create new combinations of DNA in each chromosome
71
Explain the relationship between meiosis, the segregation of chromosomes, and the transmission of alleles from parent to offspring.
During prophase 1: recombination and exchange in segments between homologous chromosomes
During metaphase 1: homologous chromosomes align randomly on metaphase plate (maternal and paternal are randomly placed on a side of the metaphase plate (pole))
The way they line up determines how they segregate in the cell and how end up in daughter cells (some have more maternal, or more paternal, etc)
Since there are infinite possibilities of assortments, there are infinite possibilities of gametes
72
what is complete dominance?
the dominant allele completely masks the effect of the recessive
73
what is incomplete dominance?
a new phenotype that is the blend of the two
73
what is codominance?
- both phenotypes are expressed (not mixed)
- no new phenotype
74
what is a centromere?
holds sister chromatids together
75
lethal alleles
dont evolve, no phenotype
76
lethal recessive alleles
no phenotype for the recessive (3:0)
77
lethal dominant alleles
Rare, since it usually results in death before reproduction (0:1)
78
epistasis
when the expression of a gene is modified (masked, inhibited or suppressed) by the expression of one or more other genes.
79
multiple alleles
- small differences in the DNA sequence of a gene which result in differences in the structure of the protein
- when a single gene is made up of 2+ alleles
80
what is the difference between the inheritance of a X-linked gene in a male and a female?
Females need to have the gene on both X chromosomes and males only need to have it on their only X
81
what is the typical ratio for incomplete dominance in F2?
1:2:1 (2 of the new phenotype)
81
what is the typical f2 for codominance?
both phenotypes expressed, no new phenotype. Half will have both
81
what is the typical f2 ratio for lethal recessive allele?
3:0 (one is dead before showing phenotype)
82
what is the typical f2 ratio for lethal dominant allele?
0:1 (3 are dead)
83
what is the typical f2 ratio in epistasis?
9:3:4
84
what does it mean if there is a skip in generation?
recessive
85
what is the particularity in X-linked recessive?
affected mother always has affected sons
86
in which way does RNA polymerase read DNA?
5' to 3'
87
which is the template strand?
3' to 5' (TAC)
88
which is the coding strand?
5' to 3' (ATG)
88
what is the start codon in coding strand?
ATG
89
what is the start codon on the template strand?
TAC
90
in which way is mRNA translated?
from 5' to 3'
91
what are the stop codons in the coding strand?
TAA, TAG, TGA
92
what are the stop codons in the template strand
ATT, ATC, ACT
93
what are the stop codons in mRNA?
UAA, UAG, UGA
94
what are the SNPs?
missense, nonsense, silent, and framshift
95
what does snp mean and how can it affect an organism?
- they affect only one gene
- single nucleotide polymorphism (not always one nucleotide, but only one gene)
96
missense mutations
- do not change reading frame
- alter the identity of one aa
- one base pair is different from normal
97
consequences of missense mutations on mRNA and protein
- an altered codon in the mRNA
- moderate to deleterious effects on protein (cannot function properly, since an aa is wrong)
98
nonsense mutation
- generates an early stop codon (premature termination)
- mutated base pair creates a stop codon
99
consequences of nonsense mutations
- stop codon created early in mRNA
- protein is truncated, not done, = severe effects on protein
99
silent mutations
- generate no change
- mutated base pair creates a changed codon but codes for same amino acid
100
frameshift mutation
- insertion/deletion of a base pair (DNA) causes reading frame to be off by one on mRNA
- aa altered due to frameshift
101
consequences of frameshift mutation
- reading frame off by one in mRNA
- rest of protein after mutation is changed
102
what are the LCRs?
deletion, duplication, translocation, inversion
103
what does LCR mean?
large chromosomal rearrangement
104
what is deletion?
- deletion of a segment of DNA
- may cause severe problems if the missing segment contains genes that are essential for the normal development or cellular function
105
what is translocation?
- a segment of DNA breaks from one chromosome and attaches to another nonhomologous chromosome
106
what is duplication?
- a segment of DNA is duplicated
- can be harmful or beneficial, depending on the genes and alleles contained in duplicated genes
107
what is inversion?
- a chromosome segment breaks and reattaches to the same chromosome, but in reverse order
- important in evolution of plants and animals
108
how can LCR affect an organism?
- affects many nucleotides
- creates a very large change in organism
109
what are the 3 steps of transcription?
initiation, elongation, termination
110
what happens in initiation of transcription?
-transcription factors bind to promoter and recruit RNA polymerase
- transcription can begin
111
what is elongation in transcription?
- RNA polymerase 2 moves along DNA in 3' to 5' to unwind it and add new RNA nucleotides from 5' to 3'
- behind, DNA reforms double helix
- hybrid DNA-RNA dimer exists briefly
112
what is termination in transcription?
- RNA polymerase is released
- we now have a pre-mRNA that still needs to be processed (releasing introns)
113
what is rRNA?
- ribosomal RNA
- in ribosomes and responsible for reading the order of aa and linking them together
- protein synthesis
114
what is mRNA?
- messenger RNA
- carry protein information out of nucleus to ribosomes
- contains protein info
115
what is tRNA
- transfer RNA
- bind to mRNA by complementary bp
- at one end of tRNA: anticodon that pairs with codon (mRNA)
- other end: binds to aa to bring it
116
what is initiation in translation?
- start codon indicates beginning (reading frame)
- establish reading frame in mature mRNA (splicing done)
117
what is splicing?
- when pre-mRNA is processed
- exons stay, introns are spliced (released)
118
what is elongation in translation?
- uses aa instead of nucleotides
- A-site: tRNA with an attached aa bind to mRNA with anticodon/codon
- P-site: peptidyl transferase enzyme forms bond between aa (from P and A site) - N bonds with C, aa cleaved from tRNA, where polypeptide is forming
- E-site: empty tRNA exists
- A-site now free to receive next tRNA
119
what are the main differences between transcription in eukaryotes and prokaryotes?
- prokaryotes don't have transcription factors
- in prokaryotes, no pre-mRNA, directly mRNA
- in prokaryotes, termination is done by mRNA that binds to a complementary sequence forming a hairpin or by a protein factor
- in eukaryotes, it is done in nucleus but it is in cytoplasm in prokaryotes
120
what is mRNA processing?
- adding a 5' cap (made of guanine) at the 5' end of the mRNA to protect it
- adding a poly-A tail (of adenine) at 3' end of mRNA
- splicing the introns (keeping only exons)
121
what is an example of prokaryotic regulation?
the lac operon
122
when does gene expression happen in prokaryotes?
at the transcriptional level
123
how can gene expression be regulated in prokaryotes?
using a repressor that binds to the promoter, stopping transcription
124
what is an operon?
sequence of genes, plus a promoter and an operator involved in the same metabolic pathway
125
what is an example of a catabolic operon?
- lac operon
- breaking down molecules
126
what is an example of an anabolic operon?
- trp operon
- synthesizing molecules
127
5 mechanisms of transcriptional control
- general transcription factors
- activators
- methylation
- histone tail acetylation
- chromatin remodelling
128
what is methylation?
- DNA methylation enzymes add a methyl group to bases of DNA.
- Methylated bases in promoter regions can prevent the binding of transcription factors, turning the gene off
129
what is histone tail acetylation?
- changes the charge on the histone tails and results in a loosening of the association of the histones with DNA
- more transcription when acetylated
130
what is chromatin remodelling?
- chromatin can be remodelled to make the promoter accessible to transcription factors and activators, increasing the transcription rate
131
what is the 5' cap?
- added to 5' end of mRNA
- protects it from degradation and is the site where ribosomes attach at the start of translation
- good for translation
132
what is the poly-A tail?
- adenine tail
- prevents mRNA from degradation when they enter the cytoplasm
- good for translation
133
how does alternative splicing contribute to protein diversity?
- the exons of a gene can be assembled in different combinations to produce different isoforms with the same gene
- this ensures protein diversity
134
what is natural selection?
- process by which advantageous traits become more common in subsequent generations
- characteristics that better enable an organism to adapt will increase
- nature selects the phenotype, not the genotype, so if hetero, both alleles are passed on
135
how is genetic drift different from natural selection?
- it is a good example of how evolution does not always select the best alleles (natural selection), because it sometimes is random
- choice of alleles in natural selection is done according to the most fit, but genetic drift allele choice is random
136
what is microevolution?
- small-scale genetic changes that populations undergo
- same species with some small differences
- any change of allele frequency within a population
- ex: different breeds of dogs
137
what is macroevolution?
- larger-scale evolutionary changes
- gradual accumulation of microevolutionary changes
- distinct species
- ex: dog, grey wolf, coyote
138
what are the 5 mechanisms of microevolution?
- natural selection,
- mutation
- nonrandom mating
- genetic drift
- gene flow
139
what are mutations?
- spontaneous and heritable change in DNA
- can be passed on to offspring
140
what is nonrandom mating?
selecting a mate with a particular phenotype (preferred by most potential mates)
141
what is an example of nonrandom mating?
sexual selection: male competition for access to females
- produces extreme phenotypes (because the chosen males have extreme phenotypes) and usually happens when population is healthy
142
what is gene flow?
- the glue that keeps populations of the same species together
- organisms or their genetic material moving from one population to another
- introduce new alleles in a population
ex: oak's accorns are carried by blue jays from one population to another
143
what is genetic drift?
chance events cause the allele frequencies in a population to change unpredictably and randomly
144
what are the circumstances that foster genetic drift?
bottleneck effect and founder effect
145
what is an example of genetic drift?
the french canadian population : created by 8500 colonists but only 4000 contributed to gene pool
146
what are the three modes of natural selection?
- directional selection
- stabilizing selection
- disruptive selection
147
what is directional selection?
- individuals near one end of the phenotypic spectrum have the highest relative fitness
- shifts the mean phenotype toward the end of the distribution favored by natural selection
148
what is stabilizing selection?
- individuals with intermediate phenotypes have the highest relative fitness
- eliminating phenotypic extremes = reduces genetic and phenotypic variation
149
what is disruptive selection?
- extreme phenotypes have higher relative fitness
- extreme phenotypes become more common = polymorphism
150
what is the morphological concept of species?
- all individuals from a same species share measurable (visible) traits that distinguish them from other individuals of other species.
- if they look the same, they are the same
151
what are the advantages of the morphological concept?
- to identify fossils
- easy to recognize them, only need to use the physical characteristics
152
what are the limits of the morphological concept?
- some are different because of their conditions even though they are the same species
- tell us little about evolutionary processes
- does not help distinguish species that look very much alike
153
what is the biological concept of species?
if the members of two populations interbreed and produce fertile offspring (naturaly), they are the same
154
what are the advantages of the biological concept of species?
- defines species in terms of population genetics and evolutionary theory
- Take gene flow into account (as long as there is gene flow, same species)
- emphasizes the genetic distinctness of species
155
what are the limits of the biological concept of species?
- does not apply to forms of life that reproduce asexually
- there are exceptions (divergent species can sometimes still breed)
156
what is the phylogenetic concept of species?
- comparing DNA % similarity
- using biological and morphological concepts
157
what are the advantages of the phylogenetic concept of species?
- applies to any group of organisms
- absence of gene flow (reproductive isolation)
158
what are the prezygotic isolating mechanisms?
- ecological isolation
- temporal isolation
- behavioral isolation
- mechanical isolation
- gametic isolation
159
what is ecological isolation?
- species live in different ecological location, so they dont meet.
- ex: polar bears and grizzlies
160
what is temporal isolation?
- species breed in different seasons, so cannot breed together
- not ready to mate at the same time
161
what is behavioral isolation?
- some species have elaborate courtship that other species dont understand, so they don't mate
- different ways to mate
161
what is mechanical isolation?
- difference in structure, shape, scent, which prevents from breeding.
162
what is gametic isolation?
incompatibility between the sperm of one species and the eggs of another
163
what are the postzygotic isolating mechanisms?
- hybrid inviability
- hybrid sterility
- hybrid breakdown
164
what is hybrid inviability?
hybrid organisms (from 2 species) often die as embryos or at a young age
165
what is hybrid sterility?
- the hybrid may grow and be normal, but cannot produce functional gametes
- cannot reproduce = zero fitness
166
what is hybrid breakdown?
first generation of hybrid is healthy and fertile, but second generation have reduced survival or fertility
167
what are the modes of speciation?
allopatric, parapatric, sympatric
168
what is allopatric speciation?
- physical barrier subdivides a large population
- 2 stages: first, they become geographically seperated, then they experience distinct mutations that isolates them reproductively
169
what is sympatric speciation?
- typically caused by change in behavior or interaction with their environment
- distinct subgroups arrise within one population
- not because of geographical isolation
170
what is parapatric speciation?
- a single species is distributed accross a discontinuity in environmental conditions (ex: change in soil type)
- natural selection may favor different alleles on either sides, limiting gene flow.
171
what is autopolyploidy speciation?
- results through an error in mitosis or meiosis
- spontaneous doubling of chromosomes produces diploid gametes
- new genes or new gene expression
- benefits plants
172
what is hybridization and allopolyploidy speciation in plants?
- different species are similar enough to fertilize one another
- creates a hybrid with nonhomologous chromosomes that don't pair up (2n = 6)
- future self-fertilization can create polyploid individuals that are reproductively isolated from both parents
173
what happens during a dihybrid cross in complete dominance?
the alleles of the genes that govern the two traits segregate independently during the formation of the gametes = independent assortment
174
what is nondisjunction?
during the first meiotic division, both chromosomes of one pair are delivered to the same pole of the spindle. It creates 2 gametes with an extra and 2 with a missing chromosome.
174
what is misdivision?
misdivision produces, during the second meiotic division, two normal gametes, one gamete with an extra chromosome and one with a missing chromosome
175
which organisms are part of eukaryotes?
protists, fungi, animals, plants
176
what is the evolutionary tree of eukaryotes?
- protists share common ancestor with plants
- animals share common ancestor with protists
177
what were the conditions present in primordial Earth and how did they possibly have favored the appearance of organic molecules?
- lightning, storms, UV radiation, presence of gases like ammonia, hydrogen, methane, volcanoes, seismic activity
- life's atmosphere (made of C-H-N) could have used the energy from lightning for example, to create macromolecules who then became living thingd
178
how was the miller urey experiment a key step in understanding life on earth?
- mimicked the conditions of the ancient Earth
- in only a week, many molecules were produced and especially amino acids, who were once thought to only be produced by life itself
- amino acids can then be created from the environment
179
how would an RNA world be sustainable on its own?
- RNA can replicate itself using complementary base pairing
- the replications can have mutations, proving that the RNA evolves
- when placed in environment without nucleotides, it folds up on itself and base pairs with itself: Ribozymes
- all of this without external help
180
what is the RNA world theory?
somewhere on early planet, random chains of RNA were produced. they began evolving and replicating and competing for survival and then gave birth to the first forms of life.
181
what are ribozymes and what do they do?
RNA folded up on itself with sticky base pairs sticking out that can interact with their environment and create nucleotides.
182
what evidence do we have in cells that support the RNA world hypothesis?
- all cells are full of RNA
- they're DNA's cousin
- they can create nucleotides
183
what were probably the first cells?
protobiont: abiotically produced organic molecules that are surrounded by a membrane.
184
how did transitions occur?
- cooperation: a group of molecules/organisms get together and form a cooperative group
- each member of the group becomes specialized and can no longer survive on its own
- now evolve together as one
185
what are the main evolutionary transitions that occurred in earth's history?
genes to genomes
simple cells to complex cells
single cells to multicellular
186
how can cooperation be selected by natual selection?
Individuals avoid getting eaten by predators by sticking together. They then become codependent and the better cooperative group will survive better.
187
how did multicellular life appear and what were its advantages?
- single cells can work together to better survive, they then evolve together as one, becoming multicellular
- better survival
188
why is biodiversity so important?
- it is all processes essential to supporting life:
air, water, food, pollination
- diversity = stability
- by being stable, they can better survive extreme environments
