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Bio unit 5 (14-17)
| Question | Answer |
|---|---|
| whats a true breeding organism | produces offspring with the same traits when self pollinated (homozygous) |
| genotype vs phenotype | phen- observable trait geno- genetic makeup, allele combo |
| testcross | crossing an unknown genotype with a homozygous recessive to determine genotype |
| monohybrid cross | cross tracking one trait |
| dihybrid | cross tracking 2 traits |
| law of independent assortment | genes different traits assort independently during gamete formation. This means the inheritance of one trait does not influence the inheritance of another, leading to diverse combinations in offspring. |
| incomplete dominance | where heterozygous genotypes produce an intermediate phenotype (a blend) rather than the dominant trait alone. Unlike complete dominance, where one allele masks another. |
| codominance | both alleles are expressed equally, 2 dom alleles affect the phenotype in separate distinguishable ways. ex- blood type AB |
| universal blood type donor/receiver | donor- O- receiver- AB+ |
| pleiotropy | one gene affects multiple traits |
| epistasis | one gene affects expression of another gene |
| polygenic inheritance | multiple genes influence one trait (ex- skin color or height) |
| nondisjunction | failure of chromosomes to separate properly during meiosis, results in abnormal chromosomes number in offspring |
| environmental effects on gene expression example | influences phenotype ex-nutrition, temperature |
| multifactorial trait | traits that are influenced by genes and the enviroment |
| what are amniocentesis or CVS used for | detect genetic disorders in a fetus |
| barr body | inactive x in female cells (condenses into a compact object called a barr body) |
| linked vs sex linked genes | linked- located on the same chromosome close together, inherited together sex linked- gene on either sex chromosome |
| recombinant phenotypes | different traits combos from crossing over |
| what happens to percent recombination for 2 genes that are very far apart on the chromosome? close together? | far apart- Max 50% close- near 0% |
| aneuoloidy | abnormal number of chromosomes |
| monosomy | missing one chromosome (2n-1) |
| trisomy | extra chromosomes (2n+1) |
| polyploidy | more than 2 complete sets of chromosomes |
| chromosomal deletion | loss of a chromosomal section |
| duplication | when a segment of DNA is copied, resulting in an extra copy of a chromosome segment |
| inversion | when a segment flips and reinserts |
| translocation | segment moves to another chromosome |
| genomic imprinting | only one allele is expressed depending on parent of origin, the other is silenced |
| how are chloroplast and mitochondrial genes inherited | inherited maternally, from the egg cytoplasm |
| whats the structure of DNA | double helix with 2 strands, sugar phosphate backbone outside, bases inside |
| what does it mean when saying DNA is antiparallel | the 2 DNA strands run in opposite directions one goes 5' to 3' while the other goes 3' to 5' |
| explain basic steps in DNA replication | DNA unwinds, strands separate, complementary strands are built, semi conservative replication |
| differences in DNA between prokaryotic and eukaryotic chromosomes | prok- single chromosome, circular eukaryotic- multiple chromosomes, linear, with histones |
| origin of replication/ how many on prokaryotes/eukaryotes | the specific DNA sequence where replication begins prokaryotes- one eukaryotes- many |
| helicase | unwinds and separate DNA strands by breaking hydrogen bonds |
| single stranded binding proteins (SSBPs) | stabilize separated DNA strands and prevent them from re connecting |
| topoisomerase | relieves tension ahead of the replication fork |
| primase | adds RNA primer to start DNA synthesis |
| Dna polymerase III | adds nucleotides to growing DNA strand in the 5' to 3' direction, reads strand 3' to 5' |
| DNA polymerase I | replaces RNA primers with DNA |
| leading strand vs lagging strand in replication | leading- synthesized continuously in same direction as the replication fork lagging- synthesized discontinuously in okazaki fragments |
| okazaki fragments | short DNA segments on the lagging strand |
| DNA ligase | joins okazaki fragments together |
| DNA repair enyzymes | fix mismatches or damage using correct strand as a template |
| what happens to lengths of chromosomes when their replicated | eukaryotic shorten with each replication because the lagging strand can't be fully replicated at the ends |
| telomere? telomerase? | telomere- DNA sequence at the ends of eukaryotic chromosomes that protect genes telomerase- enzyme that extends telomeres by adding DNA to chromosome ends (activate in germ/stem/cancer cells) |
| what can happen to telomerase in cancer cells? | it can be overactive allowing cells to divide indefinitely |
| explain DNA packaging | DNA wraps around histones, form nucleosomes, these coil into chromatin which loop and condense further to form a chromosome |
| heterochromatin vs euchromatin | hetero- tightly packed, less active in transcription euchro- loosely packed, open and accessible for transcription, used in protein synthesis |
| DNA vs RNA | Dna- double strand, thymine Rna- single strand, uracil |
| translation | using mRNA to build a protein, occurs in ribosomes In the cytoplasm or on the rough er |
| transcription | coping a genes DNA sequence into mRNA, occurs in nucleus in eukaryotes |
| central dogma | the idea that genetic information flows from DNA to RNA to proteins |
| what is the template strand when it comes to transcription | DNA strand that is used to make mRNA |
| reading frame | grouping of codons in sets of 3 |
| why is genetic code universal, how does it relate to evolution | almost all organisms use the same codons for the same amino acids which supports common ancestry |
| what makes mRNA | rna polymerase |
| promoter region | dna sequence where RNA polymerase binds to start transcription |
| terminator region | DNA sequence signaling to stop transcription |
| transcription unit | stretch of DNA that's transcribed into RNA |
| role of transcription factors | helps RNA polymerase bind to the promete and initiate transcription |
| 3 steps of transcription/translation | initiation, elongation, termination |
| RNA polymerase role in elongation of transcription | reads dna and builds complementary RNA strand |
| what modifications occur before mRNA leaves the nucleus | 5' cap is added, poly-a tail is added, introns are removed |
| what are introns and exons | introns- non coding regions exons- coding regions that are expressed |
| spliceosomes | removes introns, joins exons |
| alternative splicing | allows different combos of exons, producing multiple proteins from 1 gene |
| role of tRNA | brings amino acids to the ribosome |
| what is the anticodon | 3 nucleotide sequence found on trna that pairs with mrna codon |
| role for rRNA | make up core of the ribosome and helps catalyze peptide bond formation |
| what codon does translation begin | start codon (met/AUG) |
| what direction does the ribosome move along | 5'to3' direction |
| how many stop codons are there | 3 |
| polyribosome | group of ribosomes translating one mRNA at the same time |
| what happens after translation to proteins | folding, cutting, combining, or chemical modifications |
| role of signal recognition particles (SRPs) | directs newly synthesized proteins to the rough ER after translation |
| Point mutation (substitution) | change in one nucleotide |
| silent mutation | a substitution that doesn't change the amino acid |
| missense mutation | substitution that changes the amino acid |
| non sense mutation | changes a codon into a stop codon causing translation to stop early |
| frameshift mutations | insertion/deletion that shifts the reading frame |
| insertions | addition of 1 or more nucleotides into the DNA sequence |
| deletions | removal of 1 or more nucleotides from the DNA sequence |
| why can transcription and translation occur simultaneously in bacteria | no nucleus in bacteria eukaryotes transcription occurs in nucleus and translation occurs in cytoplasm, separated by nuclear envelope |
| define a gene | a segment of DNA that codes for a protein or functional RNA |
| RNA primase role in DNA replication | adds an RNA primers (3' end) so DNA polymerase can bind and begin synthesis |
| where is DNA found and where does transcription take place | in the nucleus |
| base pairing rules | DNA - RNA a-u, g-c DNA-DNA a-t, g-c |
| which direction is the DNA molecule read during transcription | 3' to 5' |
| which direction is RNA built | 5' to 3' |
| what parts make up the transcription initiation complex | RNA polymerase and transcription factor at the promoter |
| mRNA | carries genetic information from DNA to ribosomes |
| why are the 5' cap and poly a tail added | protects mRNA, helps export from nucleus and aid ribosome binding |
| exonucleases | an enzyme that removes nucleotides from the ends of RNA/DNA |
| where do the free nucleotides come from to form the mRNA strands | free nucleotides in the nucleus recycled or synthesized |
| how does the ribosome move during translation | reads mRNA 5' to 3' |
| why it tRNA called transfer rna | transfers amino acids to the ribosome for translation |
| how many tRNA molecules are held in a ribosome at a time | 2 usually, occasionally 3 |
| what translates codons into amino acids | ribosomes with help of tRNA |
| RNA splicing | removes introns and joins exons, creating an mRNA molecule with a continuous coding sequence |
| snRNPs | RNA protein complexes that form spliceosomes |
| aminoacyl-trna synthetase | enzyme that binds correct amino acids to tRNA |
| ribosomes | read mRNA and build polypeptides |
| parts of a ribosome | A- where tRNA enters P- where peptide bond is formed E- exit site of tRNA has a small/ a large subunit |
| initiation of translation | small subunit binds mRNA, tRNA attaches and the large subunit joins to form a complete ribosome. |
| elongation of translation | tRNAs deliver amino acids to the ribosome, peptide bonds form, the ribosome moves along mRNA to extend the polypeptide chain. |
| translocation | step during protein synthesis where the ribosome advances one codon (three nucleotides) along the mRNA. |
| termination of translation | stop codon is reached and the protein is released |
| purpose of DNA replication | to ensure identical genetic info in daughter cells |
| primary transcript | unprocessed RNA molecule synthesized from a DNA template by RNA polymerase during transcription |
| initiation of transcription | RNA polymerase binds to the promoter and begins RNA synthesis. |
| elongation of transcription | RNA polymerase moves alongs DNA adding complementary RNA nucleotides to extend the RNA strand (5'to3') |
| termination of transcription | RNA polymerase reaches a termination sequence releasing the RNA transcript |
| why are frameshift mutations ussally worse | they alter entire reading frame |
Created by:
Lilyhowes