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73 Cards in this Set
- Front
- Back
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codon
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triplets of mRNA nucleotides
genetic instructions for a polypeptide chain each triplet represents a different protein 64 possibilities |
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transcription
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DNA---RNA
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translation
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RNA---proteins
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open reading frame (ORF)
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space in between start/stop codon-has all the info necessary to create proteins
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start codon
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AUG
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stop codon
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UAA, UAG, UGA
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mutations in DNA affect on protein
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mutated
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one of the strongest arguments for evolution
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genetic code-very similar among species, redundancy
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gene
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region of DNA that carries the info needed to make one or more RNA
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stop codon
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UAA, UAG or UGA
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start codon/promoter/TATA box
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AUG-place where RNA polymerase will bind
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fRNA
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does not specify proteins. everything but mRNA
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mutations in DNA
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lead to altered amino acid sequences in proteins
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human genome
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25,000-30,000
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transcription
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DNA---RNA
bubble of unwound DNA moves along gene hits promoter (+1) where RNA polymerase binds two strands separate slightly and bubble moves down DNA until it reaches transcription stop |
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splicing
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euk splice, prok don't.
intron sequences removed, exon sequences spliced together |
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GT-AG rule
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GT-5prime end
AG-3prime tells where to start and stop splicing |
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spliceosome
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the site in the nucleus where splicing occurs
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reasons for cap and tail
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mRNA protection, export from nucleus, translatability.
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tRNA
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intermediate between mRNA and proteins...each one carries specific amino acid and interacts with RNA
3prime end covalently bonded to amino acids |
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anticodon group bonding
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hydrogen bonding between codons in mRNA and anticodons in tRNA
anticodon-triplet that uses base pairing rules |
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ribosomes
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4 RNA, ~50 proteins, broken into large and small subunits
begins to scan from the 5prime end until it finds AUG, then the first tRNA comes in and binds |
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translocation
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ribosome moves toward the 3prime end one codon at a time
keeps on going until it hits stop codon, then bonds to stop codon d trigger release of polypeptide chain and disassociation of he ribosome, tRNA and protein release factor |
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special sites in ribosome
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EPA
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average number of genes in multicellular eukaryotes
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15,000-30,000
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DNA packing problems
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DNA binds with histone and becomes very tightly packed, must be able to still fit RNA in to perform transcription
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how to solve packing problem
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"beads on a string"-nucleosomes
gets looped using scaffolding-forms a substrate on which 30nm fiber can form a tube further looping by scaffolding centromere: around middle of chromosome telomere: on the ends |
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histone octamer
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8 nucleosomes (proteins)
H2A, H2B, B3, H4-pair of each also H1 associated with nucleosome core and linker DNA wraps around roughly twice (bead on a string) small/positively charged/highly conserved |
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human genome
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5% genes
5% simple sequence repeats 45% interspersed repeats 45% unique sequence |
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heterochromatin vs euchromatin
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eu=good, used chromatin, used genes, stays packed tightly
h=bad, unused chromatin, highest concentration of both around centromere and telomere |
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transposons
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mobile pieces of DNA, can cause mutation by jumping into a gene
10% of human genome is a million copies of a 300bp transposon called "Alu" |
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gene duplication/divergence
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duplication-produce families of related genes at the same place in the genome
divergence-gradual change...mistakes in replication can end up in positive or negative changes |
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pseudo genes
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supports duplication/divergence theory. went through drift process but ended up as junk. no longer functional genes
human genome has ~20,000 pseudo genes |
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solenoid
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packing of DNA as a 30nm fiber (bead on a string phase)
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housekeeping gene
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needed to produce ATP. in every cell.
non housekeeping genes=regulated genes |
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chromatin
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must be loosened before gene can be transcribed
adding acetyl---looser formation, genes transcribed attaches to histone tails |
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distal control elements
activator transcription factors |
regulates when promoter should be used. can be close or very far away
protein that bonds to distal control TF-proteins that bond to activators and sequences around promoter combination of ^^^ in order for RNA polymerase to bind |
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why cells divide using mitosis (3 reasons)
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reproduction-unicellular amoeba divides to make two identical amoebae
development-fertilized embryo renewal |
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alpha vs beta gene families
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alpha-chromosomes 11, 3 active genes
beta-chromosomes 16, 5 active genes |
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hemoglobin
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heterotetramer- 2 alpha 2 beta globins
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globin genes pregnancy ex
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Different globin genes are expressed at different times during development, allows fetus to grab oxygen from mother's blood
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spindle
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made of microtubules
"ropes” that form a scaffolding along which the chromosomes can move in order to be duplicated created by centrosome connected by spindle fibers |
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kinetochore
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part of the centromere where the chromosome attaches to the spindle
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metaphase
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chromosomes attached at equator
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anaphase
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centromere splits, two sister chromatids go to opposite poles (established by centromere)
movement of chromosomes is powered along spindle fibers, not being pulled to poles |
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telophase
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all chromosomes have reached a pole
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cytokinesis
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cleavage furrow appears at equator, new membrane is formed.
plant mitosis-cell plate grows from middle |
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diploid/haploid
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d=2 copies of each gene
h=one copy of each |
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autosome
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non sex chromosomes
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karyotype
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spread of chromosomes arranged by size and centromere position
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meiosis vs mitosis in cell production
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mitosis-2
meiosis-4 |
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two functions of meiosis
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halve chromosome number and create diversity
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meiosis 1
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homologous chromosomes pair up during prophase, seen at the metaphase plate-two chromosome 3's pair up and two chromosome 11's
the pair separates from each other, moves to opposite poles (halving of chromosomes) |
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synapsis
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tight pairing of homologs
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meiosis 2
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same as mitosis-each chromosome sits on its own at metaphase plate, sister chromatids separate and move to opposite poles
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crossing over
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occurs during meiosis 1-exchange of homologous parts of non sister chromatids
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chiasma
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site of crossing over (recombination)
if genes are close together, unlikely to recombine, far apart more likely |
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variation in meiosis vs mutation
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meiosis-shuffles pre existing variation
mutation-introduces new variation |
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gametes
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haploid, will have one of each homologous pair of parental chromosomes
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recessive
dominant |
R-mutant allele showing in phenotype
D-wildtype allele showing in phenotype recessive mutations common because genes are haplosufficient |
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haplosufficient
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50% of gene product is enough to get the same phenotype as 100%
limited amount of substrate, so half the enzyme can still convert all the substrate into product |
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haploinsufficient
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half the amount of enzyme available in the heterozygote than the homozygote, can't produce as much
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interference
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mutant protein binds to and inhibits the wild type protein-dominant negative allele
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pleiotropy
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single gene, many effects
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polygenic/quantitative traits
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traits determined by many genes combining with the environment
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how to tell if a phenotype in a population is polygenic
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plotting the frequency-bell shaped curve-many ways of getting a mix of contributing alleles
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chromosome theory of inheritance
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behavior of genes/alleles in meiosis matches behavior of chromosomes in meiosis
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sex linkage
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genes on the X don't have a counterpart on the Y. X and Y act as homologous pair, males produce sperm carrying either one
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linked genes
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genes on the same chromosome
whatever combination of alleles are on that gene will tend to stay the same because only way to change them is crossing over there will ALWAYS be fewer recombinants than parental |
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how to calculate the distance between genes
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distance=frequency of recombinants in a cross
recombination frequency=(# of recombinants/total) X 100 |
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result of crossing a heterozygote for two genes and a homozygous mutant for same two genes
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two recombinant classes and two parental
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viruses
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non living parasitic organisms-depend entirely on the cell they infect to reproduce
inert outside of cell great variation in morphology genome may be RNA or DNA |
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capsid
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protein coat surrounding genome
might have membrane envelope around it |
