final exam Flashcards
relationship between properties of lipids and their structure
-made of c h and o
-fatty acid are more solid the longer their carbon chain is
-saturated fats acid have max h on all c and unsaturated don’t
-non polar molecules so makes them water insoluble except phospholipids that have dual solubility as they have a polar head so hydrophilic and non polar hydrophobic tails
-steroids are lipid hormones that can diffuse through the cell membrane
relationship between properties of carbohydrates and their structure
-c h and o in 1;2:1 ratio
-polar molecules so highly soluble;e in water
-polysaccahrides of monosaccharides linked by dehydration synthesis reaction
major fuel substances
carbohydrates and fats as well as protein if others are low provide chemical energy for cellular activity
relationship between properties of proteins and their structure
-polymers of amino acids
-link between each amino acid is a peptide bond between nh2 and cooh by dehydration synthesis
-chain of amino acid=polypeptide
-protein=folded polypeptide
-amino acids are made of a central carbon linked to an r chain, a cooh, a h, and an nh2
-4 types of amino acids; non polar, uncharged polar, negatively charged acidic and positively charged basic
relationship between properties of nucleic acids and their structure
-polymers of nucleotides
-nucleotide consists of a nitrogenous base made with carbon rings and n atoms, a five carbon ring shaped sugar and 1 to 3 phosphate groups all linked through covalent bonds
-backbone of a nucleic acid is made by the bridging phosphate group between carbon of one sugar and carbon of the next between dna and rna
cellulose and chitin function
rigidity and support (beta linkage)
function glycogen and starch
fuel storage (alpha linkage)
bacteria and archea similarities
-dna is a single circular molecule (prokaryotic chromosome)
-no cytoplasmic organnelles
-cytoplasm more viscous as reactions are carried out in cytoplasmic solution and plasma membrane so lots of macromol there
-contain plasmids (small dna circles)
-genes arranged in operons
-no nuclear envelope
bacteria archea eukarya similarity
-have ribosomes
bacteria
-phospholipid cell membrane (flexible)
-peptidoglycan cell wall (rigid) (polymer of sugars and amino acids)
-bacteria probably first organism on earth
-shape is most important classification criteria
-
archea
-extremophiles
-
eukarya and archea
-both have histones
-no peptidoglycan
-multiple types of rna polymerase
-have methionine as first amino a of each protein
eukarya
-separate dna and cytoplasm with nuclear envelope
-have membrane bound components (organelles) with specialized functions
-protists, fungi, plants, animals
protists
-chemoheterotrophs (take energy from chem bonds between molecules and obtain carbon from org mol produced by other organisms)
-photoautotrophs (produce org molecules for themselves by photosynthesis)
-membrane bound nucleus and multiple linear chromosomes
fungi
-chitin made cell wall
-can do symbiose and associate with like plant and make micorrizhas
-heterotrophs (get carbon by decomposing org matter) if the decomposed material is living the fungi is symbiont and if its nonliving its sapotroph
-fungi release antibacterial compounds so that there is no competition for the enzymes it releases into its substrate
animalia
-eukaryotic multicellular organisms
-dont have cell wall so cell membranes of adjacent cells are in direct contact with one another
-heterotrophs (depend on other life forms to survive)
-use oxygen to metabolize food
-animals are motible
reproduce sexually or asexually
-sit at top of food chains
-chemoheterotrophs (energy from chem sources and their carbon from org compounds)
plantae
-use chlorophyll to do photosynthesis
-cell walls made of cellulose
-multicellular
-sessile or stationnary
-alternation of generations life cycles
-diploid and haploid stage
-photoautotrophs
bottom of food chains and primary producers
base pairs from dna to rna
a to u
t to a
c to g
g to c
different types of snp
base sub
frameshift mutations
missence mutations
base sub
alters identity one amino acid
does not change reading frame
moderate to deleterious effects on the protein
nonsense mutation
base sub
generates early stop codon
protein is truncated
severe effects on protein function
silent mutation
base sub
generates no change
protein identical so no effect
frameshift mutations
insertion or deletion
changes the reading frame as a premature stop codon will be produced
types lcr
deletions
inversions
translocation
duplications
deletion
-occurs if segment broken and lost from chromo
-may cause severe problems if the missing segment contains genes that are essential for normal development or cellular function
duplication
-occurs if a segment is broken from a chromo and added to the homologous chromo of the pair
-effects vary from beneficial to harmful depending on the alleles and genes in broken segment
translocation
-a segment breaks from a chromo and reattaches on another non homologous
inversion
-occurs if a broken segment attaches on the same chromosome but in reverse orientation
start codon on mRNA
AUG
first step transcription
initiation
transcription factors bind to TATA box in promoter and recruit RNA polymerase II that will initiate transcription
second step transcription
elongation
rna polymerase 2 unwinds the dna strands and adds new complementary base pairs to the newly formed mrna strand
last third step transcription
termination
rna polymerase is released and the dna rewinds
differences in transcription in prokaryotes and in eukaryotes
-proka: no transcription factors, rna polymerase binds directly to promoter to start transcription
-proka: no need for mRNA processing, its ready to be translated
-termination in proka is done either by mrna binding on itself forming a hairpin and releasing the polymerase or by a protein factor terminating transcription
rna polymerase 1
transcribes dna into rrna
rna polymerase ii
enzme used to transcribe protein coding genes
dna to mrna
rna polymerase iii
enzyme used to transcribe dna into trna and rrna
rrna
composes the ribosomes
trna
what brings the amino acid to the ribosomes
transcription
from 3’ to 5’ dna to 5’ to 3’ mrna
translation
5’ to 3’ mrna to protein starting by N and ending by c
role ribosome
facilitate the interaction between mRNA and Trna and hold the growing mRNA
what happens inside the ribosome
1 trna molecule bringing the amino acid that matches the codon on mrna enters the ribosome in A site
2 the amino acid is transferred to the growing polypeptide chain in the p site
3 once the transfer is complete the ribosome moves along the mrna while the trna exists through the e site
first step translation
initiation
-a specialized methionine bound to a gtp initiates translation
-the ribosomes scans mrna to find start codon and establish. correct reading frame
second step translation
elongation
what happens through ribosome is elongation
third step translation
termination
when ribosomes finds stop codon, there is a release factor that releases polypeptide
polysome
complex of multiple ribosomes that makes for a faster translation
PolyA tail
-post transcriptional and translational control
-The polyA tail prevents the degradation of mRNA when it enters the cytoplasm.
-The length of the polyA tail will modulate the translation rate of the mRNA. A polyA tail contains between 50 and 250 adenine nucleotides. The longer the polyA tail, the higher the translation rate.
5’ cap
The addition of a 5’ cap prevents the degradation of mRNA when it travels to the cytoplasm.
dna methylation
-transcr control
Adding methyl groups on the cytosine nucleotides of the promoter prevents transcription factors from binding to the promoter and thus prevents RNA polymerase from initiating transcription.
histone tail acetylation
-transc control
- Acetylating histone tails enables RNA polymerase to circulate on the mRNA molecule, which is impossible to do when the histone tails are not acetylated.
chromatin remodelling
trancr control
Chromatin can be remodeled to make the promoter accessible to transcription factors and activators, increasing the transcription rate.
Splicing
post transcr control
By removing the introns from the mRNA, a complete and continuous open reading frame is produced, ready for the ribosome to translate. Splicing is performed by the spliceosome, a multiprotein complex containing snRNPs designed to interact with the splice sites of mRNA polymers.
mechanisms of microevolution
mutation
gene flow
genetic drift
natural selection
non random mating
mutations u4
-spontaneous and heritable change in DNA
-rare, even more rare are new mutations
-classified based on the effect they have on an organism’s fitness
-have an effect on the long term as they are transferred to offsprings
types of mutations
-harmful; alter individual’s structure, behaviour or function in harmful way
-lethal; great harm to organism
-neutral; doesn’t harm or benefit organism
-advantageous
non random mating
selection of a mate as certain phenotypes are preferred.
if one phenotype preferred by MOST than nonrandom
sexual selection occurs when pop is healty, it creates extreme phenotypes
-inbreeding: genetically related individuals breeding
-self fertilization: extreme inbreeding as 1 individual’s gametes are used
gene flow
-organism immigrating to another population and reproducing creates gene flow
genetic drift
-causes allele frequencies of a pop to change unpredictably
-individuals/alleles survive and reproduce by chance and not fitness
-bottleneck effect: kills off large part pop and greatly reduces genetic variation
-founder effect: when few individuals colonize region, they bring only few alleles
natural selection
-process by which advantageous traits become more frequent in later generations
-some organisms might die and not pass on their alleles as they are not fit to survive
how does genetic drift contrasts with natural selection in terms of allele frequencies
natural selection chooses alleles that are advantageous for following generations, they make the org better fit to survive whereas genetic drift can negatively affect the following generations as it might not choose the best alleles
types natural selection
disruptive: intermediate dies as extreme phenotypes are more fit
stabilizing: extremes die as intermediate phenotypes are more fit
directionnal: one extreme dies as the other has better fitness
macroevolution
leads to speciation
accumulation of microevolutionary changes
microevolution
small changes that leads to different organisms in a specie (types of dogs)
prezygotic reproductive isolating mechanisms
ecological isolation: species have different habitats and dont meet
behavioral isolation: courtship mech of some species aren’t recognized by other ones
temporal isolation: species dont mate in same season
mechanical isolation: species cant physically mate
gametic isolation: species have nonmatching receptors on gametes
postzygotic reproductive isolating mechanisms
hybrid inviability: very short lifespan
hybrid sterility: cant produce functional gametes and reproduce
hybrid breakdown: F1 will look healthy and live but f2 will experience reduced survival and fertility
modes of speciation
allopatric
parapatric
sympatric
autopolyploidy
allopolyploidy
allopatric speciation
2 populations get geographically preventing gene flow
and accumulate genetic differences that isolate them reproductively
sympatric speciation
this reproductive isolation evolves between distinct subgroups in one population
parapatric
caused by a discontinuity in environnemental conditions
autoployploidy
when 2 organisms are which genetically close enough together can repdosuce and make an hybrid with a bigger ploidy
allopolyploidy
chromo are doubled in mitosis
different concepts of species
morphological
biological
phylogenetic
morphological concept
based on the physical appearance of a species and the traits they share, however doesnt help distinguish closely related species and it tells us little about the evolutionnary processes that produce new species
biological concept
says that if two pop interbreed and produce fertile offspring, they are of same specie
emphasizes the genetic distinctivness of each specie
does not work for specie that reproduce asexually or hybrids
the phylogenetic concept
using morphology and genetic sequence data it creates an evolutionary tree
can apply to extinct species and those that reproduce asexually
duplicated vs unduplicated chromosomes
duplicated 2N has the form of a X, 2 sister chromatids
unduplicated 2n has form of I, 1 chromatid
how are the chromosomes in G1of interphase of mitosis
unreplicated uncondensed 2n
how are the chromosomes in G2 of interphase of mitosis
replicated unattached uncondensed 2N
how are the chromosomes in prophase of mitosis
2 sister chromatids attached by centromere condensed and visible 2N
how are the chromosomes in prometaphase of mitosis
2 sister chromatids attached by centromere condensed and visible 2N and attached to kinetochores
how are the chromosomes in metaphase of mitosis
2 sister chromatids attached by centromere condensed and visible 2N aligned
how are the chromosomes in anaphase of mitosis
2 separated sister chromatids 2N->4n
how are the chromosomes in telophase of mitosis
4n and chromo go back to being chromatin
function mitosis
cell divides into 2 identical cells
growth
injury repair
replacement of worn out cells
functions meiosis
gamete formation so in testes and ovaries
creates genetic diversity
reproduction
g1 of interphase of mitosis
before dna replication
growth of rna proteins and organelles
s phase mitosis
each chromosome is replicated
g2 of interphase of mitosis
special proteins check for mistake dna, if there is, cell duplication stops there
centrioles duplicates
prophase of mitosis
chromo condense into threads that become visible
centrosomes start to separate and form spindle
prometaphase of mitosis
nuclear enveloppe disappears and spindle enters the former nuclear area
microtubules from the opposite spindles attach to kinetochores of chromosomes
metaphase of mitosis
chromosomes align on metaphase plate/spindle midpoint
kinetochore microtubules try pulling apart the sister chromatids
anaphase of mitosis
sister chromatids are separated from one another and moved to opposite poles by spindle
telophase of mitosis
chromosomes unfold and return to chromatin and nuclear envelopes reform the cytoplasm starts separating in two cells because of furrowing
condensation of chromosomes in prophase of meiosis 1
chromo are 2N so duplicated sister chromatids
centrioles are duplicated
chromo condenses
synapsis is prophase 1 of meiosis 1
homologous chromosomes come together and pair to form tetrads (4 sister chromatids of an homologous chromosome)
2N
recombination of prophase 1 of meiosis 1
chromatids of homologous chromosomes exchange segments
2N
prometaphase 1 of prophase 1 of meiosis 1
nuclear envelope breaks down and spindle goes to former nuclear area
kinetochore microtubule attach to chromosomes (tetrads)
2N
what creates genetic diversity
the independant assortment of chromosomes
recombination
metaphase of meiosis 1
spindle microtubules align the tetrads on metaphase plate
2N
anaphase of meiosis 1
spindle microtubules separate two chromosomes of each homologous pair and move them to opposite spindle poles
poles now contain haploid number of chromosomes (each chromo still contains 2 sister chromatids)
2n
telophase of meiosis 1
spindle of first meiotic division disassembles and 2 new spindle form for second division
2N->1N
cytokinesis of meiosis 1
cleavage furrow separates in two cells
prophase of meiosis 2
chromosomes recondense and spindle forms
1N
metaphase of meiosis 2
the spindle microtubules align the chromosomes on metaphase plate
1N
anaphase of meiosis 2
spindle microtubules separate the two chromatids od each chromosome and deliver them to opposite spindle poles
1N -> 2n
telophase of meiosis 2
chromosomes decondense and separate in 4 cells of 1n and new nuclear envelopes form
gene
unit containing the code for a protein molecule or one of its parts, or for functioning rna molecules such as tRNA or rRNA
allele
version of a gene
genotype
genetic constitution of an individual, the different allele an individual has
phenotype
outward appearance of an organism, the genes showed
trait
heritable variation in character
homozygote
2 identical alleles for the same gene
heterozygote
2 different alleles for a gene
autosome
non sexual chromosome
sexual chromosome
x or y
complete dominance
all the same in F1 and 3;1 ratio in f2
epistasis
genes interact and some alleles block the appearance of a trait or enhance it
incomplete dominance
heterozygote individuals will show a new phenotype
f2 ratio 1;2;1
codominance
both phenotypes are expressed 1:2:1 f2 ratio
lethal alleles
can result in death of carrier
multiple alleles
differences in the dna sequence of a gene at one or more points which results in detectable differences in the structure of the protein encoded by the gene
4 inheritance patterns of pedigrees
autosomal dominant
autosomal recessive
x linked dominant
x linked recessive
autosomal dominant
allele for trait carried on autosome and is dominant
autosomal recessive
allele for the trait carried on autosome and is recessive
x linked recessive
allele for trait carried on x chromosome and is recessive
x linked dominant
allele for the trait is carried on sex chromosome x and is dominant
pedigree square
male
pedigree round
female
darkened shape
affected
pedigree skips generation
recessive
pedigree recessive more men affected than female
x linked recessive
pedigree recessive and mother has an unaffected son
definetly not x linked
pedigree dominant and affected father has unaffected daughter
not x linked dominant
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
pedigree if unsure
most probably…
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 things
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
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.
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.
what evidence is in our cells and supports the rna wolrd hypothesis
-all cells are full of RNA
-they’re DNA’s cousin
-they can create nucleotides
what were probably the first cells?
protobiont: abiotically produced organic molecules that are surrounded by a membrane.
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
what are the main evolutionary transitions that occurred in earth’s history?
genes to genomes
simple cells to complex cells
single cells to multicellular
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.
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
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
lac operon induced or repressible and what type rxn
induced and catabolic
trp operon induced or repressible and what type rxn
repressible and anabolic
what happens to the lac operon when no lactose
the Lac repressor encoded by the LacI gene is active and binds to the operator so no transcription really occurs (basal level)
what happens to the lac operon when lactose present
the lactose is converted to allocase which inactivates the repressor so it does not bind to the operator so transcription can occur
what happens the trp operson when there is no trp
the repressor is inactive, so it is prevented from binding to the operator so transcription can happen
