bio181test4

records genetic relationships among the individuals in a family along with each person's sex and phenotype with respect to the trait in question

• individuals with trait must be homozygous
• if parent of affected do not have trait, parents heterozygous

allele responsible is likely to be ressive and found on the x chromosome

skips a gemeration in a pedigree

DNA

studied how virus T2 infects E.Coli, to determine if genes made of DNA or protein by seeing what T2 had enter host cell. Showed that DNA is hereditary material

made of monomers called deoxyribonucleotides (have deoxyribose, sugar, molecule, phosphate group, nitrogenous base. Link into polymer wed phosphidiester bond forms between hydroxyl group on 3' carbon and phosphate to 5' carbon

polarity (directionality) one end has exposed hydroxyl group on 3' carbon of deoxyribose, other has exposed phosphate group on 5' carbon.

each new daughter DNA molecule consist of one old and one new. (One strand used as template for synthesis of new)

results in intact parental molecule and a daughter DNA consisting of newly synthesized strands. ( strands toward outwear to serve as template, then turn back)

parent helix cut into short sections before being unwound and copied, new and old segment alternate. old dan with new dan

• tested to see how DNA replicated using different isotopes of nitrogen. if conservative, daughter cells have either 14N or 15N, not both.
• If semiconservative or dispersive, all DNA contain equal mix.
• second generation-semiconservative have only have 14N, dispersive just one band
• show that DNA molecule comprises one old strand and one new strand (semiconservative)

polymerized deoxyribonucleotides to DNA. can add deoxyribonucleotides to only 3' end of a growing DNA chain, DNA synthesis always proceeds from 5' -> 3'

site on a chromosome at which DNA replication begins

Y-shaped region where parent DNA double helix is split into two single strands , which are then copied

deoxyribonuclepside triphosphate

breakes hydrogen bonds between base pairs, causing DNA strands to separate

attach to separated strands and prevent them from snapping back into a double helix

enzyme that cuts DNA, allows it to unwind, and rejoins it ahead of the advancing replication fork. relieves twisting forces caused by the opening off the helix

required by DNA polymerase, consists of a few nucleotides bonded to template strand, provides free 3' hydroxyl group that can combine with an incoming dNTP to form phosphodiester bond

catalyzes the synthesis of the RNA primer ( type of RNA polymers)

enzyme that catalyzes the polymerization of ribonucleotides into RNA, not need primers

(continuously synthesized) 3' to 5' strand (synthesized 5' to 3')

synthesized in opposite direction of replication fork (5' to 3' strand of DNA) synthesized discontinuously

starts when primes synthesizes short stretch of RNA for primer, DNA polymerase III adds base to 3' end of primer

short segment of DNA produced during replication of 5' to 3' template strand. make up lagging strand in newly synthesized DNA

extends leading strand

Holds DNA polymerase in place during strand extension

catalyzes synthesis of RNA primer on okozaki fragment

extends Okazaki fragment

holds DNA polymerase in place during strand extension

removes RNA primer and replaces it with DNA

Catalyzes joining of Okazaki fragments into continuous strand

• region at the end of chromosome, do not contain genes that code for products needed in the cell
• single stranded DNA remains after telomeres degrade, result in shortening of linear chromosomes

catalyzes synthesis of DNA from RNA template

somatic cells

proofread (done by epsilon subunit, acts as exonuclease and removes wrong nucleotide if -OH group is free)

occurs when mismatched bases are corrected after DNA synthesis is complete. (other group of enzymes complete)

genes are under chemical attack, radiation, ect (nucleotides excision, followed by replacement and linkage)

knock-out,null, or loss of function alleles

(Beadle and Tatum) claimed that genes contain information needed to make proteins, many of which function as enzymes.

RNA molecule that carries encoded info, transcribed from DNA, that specifies the amino acid sequence of a polypeptide

synthesizes RNA molecules according to the information provided by the sequence of bases in a particular stretch of DNA

• summarizes flow of information in cells ( DNA -> RNA -> Proteins)
• DNA is hereditary, Genes consist of stretches of DNA that code for products used, sequence of bases in DNA specify sequence of bases in RNA, sequence of bases in RNA specify sequence of amino acids in the protein, in this way genes code for proteins

process by which permanent info found in the DNA molecule is copied to the short-life information carrier molecule, mRNA

process by which information contained in RNA molecule is transferred to type of molecule (protein)

sequence of bases in its DNA

proteins it produces

variation in DNA sequences

more than one codon might specify same amino acid

codon never codes for more than one amino acid

with few minor exceptions, all codons specify the same amino acids in all organisms

single base change

point mutation that causes a change in the amino acid sequence of a protein (replacement mutation) can be beneficial neutral or deleterious

mutation that does not detectable affect the phenotype of the organism (usually neutral)

change in nucleotide that results in early stop codon usually deleterious

addition or deletion of a nucleotide usually deleterious

strand that is read by the enzyme, RNA polymerase

its sequence matches the sequence of the RNA that is transcribed from the template strand and codes for a polypeptide

genes that code for most of the large RNA molecules (rRNA) found in ribosomes)

protein coding genes (produce mRNA) genes that code for RNAs that function in ribosome assembly, and in processing and regulation of mRNAs

genes that code for transfer RNAs(tRNAS) for pme pf the s,a;; rRMAs found in robosomes and for noncoding RNAs (ncRNAs), also genes that code for RNAs that function in ribosome assembly and in processing and regulation of mRNAs

bacterial RNA polymerase is a large globular enzyme with several channels

a detachable protein subunit called sigma must bind to polymerase

formed by bacterial RNA polymerase and sigma. consists of a coreenzyme (contains active site for catalysis and other required proteins)

promoters

centered about 30 base pairs upstream of the transcription start site, many of eukaryotic promotors have

SIgma, not RNA polymerase (supports hypothesis that sigma is a regulatory protein)

bind to a different type of promoter and therefore a different kind of gene

initiate eukaryotic transcription by binding to the appropriate promoter region in DNA. assembles st promoter first, the RNA polymerase

DNA helix opens. beginning transcription

RNA polymerase moves along the DNA template in the 3' -> 5' direction but synthesizes RNA in the 5' -> 3' direction

termination phase, RNA polymerase encounters a transcription termination signal that causes the RNA to form a hairpin structure

directly, in eukaryotes it isn't

region of eukaryotic gene that is translated into a peptide or protein

region of eukaryotic gene that is transcribed into RNA but is later removed, so it is not translated into a peptide or protein

splicing

protein-plus-RNA complexes

snRNPs bing to 5' exon-intron boundary, more arrive to form complex called spliceosome. The intron forms a loop with the key adenine at its connecting point, and then the loop is cut out and a phosphodiester bond links the eons on either side, producing a contiguous coding sequence.

structure called the 5' cap.

poly(A) tail

processing of the primary RNA transcript is complete and the product is a mature mRNA

ribosomes

concurrently because there is no nuclear envelope to separate the two processes, physically connected

separate, transcripts are processed to produe mature mRNA, which can be used to begin translation. separate in time and space

bacteria: 1 eukaryotes: 3, each different RNA

• bacteria: typically contains a -35 box and a -10 box
• Eukaryotes complex and variable, TATA box

• bacteria: sigma, different versions bind to different promoters
• Eukaryotes many basal transcription factions

• bacteria: none
• eukaryotes: extensive, cap splicing and addition of tail

picks up specific amino acid and binds to the corresponding codon in messenger RNA during translation

• input of energy (ATP) required to attach amino acid to tRNA
• enzymes called aminoacyl tRNA syntheses catalyze addition of amino acids to tRNAs, for each of 20 amino acids, different aminoacyl tRNA synthetase and one or more tRNAs

combination of a tRNA molecule covalently linked to an amino acids.

a CCA sequence at 3' end of molecule offers binding site for amino acids, while codon at loop at far end serve as anticodon ( set of three ribonucleotides that form base pairs with mRNA codon)

protein and ribosomal RNA (rRNA)

where peptide-bond formation takes place

holds mRNA in place during translation

three sites in ribosomes

anticodons to corresponding mRNA codon

acceptor site for an aminoacyl tRNA

where peptide bond forms that adds an amino acid to the growing polypeptide chain

where tRNAS no longer bound to an amino acid exit the ribosome

• 1. aminoacyl tRNA diffuses into A site, anticodon binds to a codon in mRNA
• 2. peptide bond forms between the amino acid held by the aminoacyl tRNA in the A site and the growing polypeptide, which was held by a tRNA in the p site
• 3. The ribosome moves ahead, three tRNAs move one position down line. tTRNA in e site exits, tRNA in p site moves to E, and tRNA in A site switches to P site.

mRNA binds to small ribosomal subunit, initiator aminoacy tRNA bearing f-met binds to start codon, and large ribosomal subunit binds, completing the complex.

P site, e and a site empty

initiator tRNA binds to P site, aminoacyl tRNA binds to the codon in the A site via complementary base pairing between anticodon and codon, and peptide bond formation occurs between amino acids on the tRNAs in the P and A sites

the amino acids on the tRNAs are in the ribosome's active site. This is where peptide bond formation, the essence of protein synthesis, occurs

RNA, ribosome is a ribozyme, not an enzyme

moves empty tRNA into E site, moves tRNA containing the growing polypeptide into P site, and opens A site and exposes new mRNA codon. \

starts when A site encounters stop codon, causing protein called release factor to enter site (resembles tRNA in size and shape but does not have amino acid), which catalyze hydrolysis of bond linking tRNA in P site with polypeptide chain