Genetics Unit 3

what are the four criteria for genetic material?

information, transmission, replication, and variation

describe Gtiffeth’s experimental design?

injected mice with four different variations of a bacteria, one live S, one live R, one heat killed S, and one heat killed S with life R

describe the results of Griffeths experiment

mice with Live S died

mice with Live R survived

mice with heat-killed S survived

mice with heat-killed S+ live R died

what principle did Gritth’s experimental results establish?

transforming principle, some material gives the properties of one cell to another

what are the four types of changes in chromosome structure?

deletion, duplication, inversion and translocation

What chromosome deletion?

loss of chromosome segment

What is a chromosome duplication?

abnormal repetition of a chromosome sequence

how are chromosome deletions and duplications similar?

both change the total amount of genetic material

what are chromosomes inversions?

a changes in the direction of genetical material while remaining on the same chromosome

what are chromosome translocations?

when a segment from one chromosome becomes attached to a different chromosome

how are inversions and translocations similar?

both rearrange genetic material but maintain the total amount remains the same

what are the two types of chromosome deletion?

terminal (at the end of a chromosome) and interstitial (in the middle of a chromosome)

what is the difference between paracentric and pericentic inversion

paracentic does not involve the centromere while pericentric does involve the centromere

what is the breakpoint effect?

when the split causes a gene to be non-functional

what I the position effect?

when the repositioning of a gene alters the intensity of it’s expression

what are the types of translocation?

nonreciprocal, reciprocal, robertsonian

what is non-reciprocal translocation?

when one section of chromosome moves to another non-homologous chromosome

what is reciprocal translocation

when segments of equal amounts are swapped between non-homogous chromosomes

what are the two mechanisms of reciprocal translocation?

repair of broken chromosomes and abnormal crossover between non-homologous chromosomes

what is aneuploidy?

variation in the number of chromosomes within a set

what is euploidy?

variation in number across every set of chromosome

what are the two types of aneuploidy?

trisomic and monosomic

what is trisomic aneuploidy?

3 copies of a chromosome

what is monosomic aneuploidy

1 copy of a chromosome

describe robertsonian translocation?

when the short arm of one chromosome is exchanged with the long arm of another, leaving one large chromosome and one fragment that is often lost

what does aneuploidy tend to cause phenotypic effects?

it causes over or underproduction of a gene expression

describe Avery-MacLeod’s experimental design ?

heat-killed S cells were mixed with R cells and an enzyme to kill either DNA, RNA, or proteins, if there continued to be cell growth then transformation was not occurring

what were the results of Avery-MacLeod-McCarty’s experiment?

the cells mixed with DNAse saw no growth while those mixed with RNAse or protease continued to grow

what was the implication of the Avery-MacLeod-McCarthy experiment?

that DNA was the transforming material

describe the experimental design of the Hershey-Chase experiment?

bacteriophages were grown with their protein being radioactive sulfur and protein labeled in radioactive phosphorus and introduced to new cells. Cells were blended to seperate

what were the results of the Hershey-Chase experiment?

only phosphorus 32, attached to DNA was involved in the replication of new particles

what did the results of the Hershey-Chase experiment confirm?

that DNA in hereditary material?

which experiments contributed to discovering the role of DNA

Griffeth, Avery-MacLeod-McCarthy, and Hershey-Chase

which experiments contributed to the discovery of DNA’s structure?

Chargoff, Frankin, Watson and Crick

describe the structure of Chargoff’s experiments

nucleic acids were isolated, purified ad their composition measured

what was the results of Chargoff'‘s experiments?

% of adenine was equal to % thymine, % of cytosine was equal to % of guanine

what rule emerged from Chargoffs experiment?

adenine always pairs to thymine, cytosine pairs to guanine

what were the results of Franklins experiments?

helical shape with consistent width between bases

sugar phosphate backbone on the outside of the bases

what were the results of Watson and Crick’s experiment

the full structure of DNA+ it runs anti-parallel

what are the key features of DNA?

double helix-two strands twisted together

complimentary bases hydrogen bonded to each others

major and minor asymmetrical groves

deoxyribose sugar

nitrogenous bases

phosphate backbone

what are the key features of RNA

usually single stranded

ribose sugar

nitrogenous based, uracil instead of thymine

phosphate group

what are the possible types of double-stranded RNA?

bulge loop, internal loop, multi branch loop, stem/hairpin loop

what is a nucleotide?

the structural unit of both DNA and RNA

what are the components of a nucleotide?

phosphate group, pentose sugar, nitrogenous bases

what bases are purines?

adenine and guanine

what bases are pyrimidines?

cytosine and thymine

what base is this?

adenine?

what base is this?

guanine

what base is this?

cytosine

what base is this?

thymine

what base is this?

uracil

what is the primary difference between purines and pyrimidines?

purines have two rings, pyrimidines have one

what bases are in DNA

Adenine, Guanine, Cytosine, and Thymine

what bases are in RNA

adenine, guanine, cytosine and uracil

what are the functional sites on a prokaryotic chromosome?

origin of replication, repetitive sequence, intergenic regions

what is the origin of replication?

the location DNA replication begins

what are repetitive sequences?

sequences of DNA that don’t code for specific genes

what are antigenic regions?

short regions between adjacent genes?

what are micro domains?

coils formed by Nucleoid-associated proteins that compact chromosomal DNA 1,000 fold

what is DNA supercoiling?

formation of additional coils in addition to loop domains

what is the role of DNA Gyrase?

to form negative supercoils using ATP and relies positive supercoils

what is the role of DNA topoisomerase I

relaxes negative supercoils

what are the functional sites of eukaryotic chromosomes?

origin of replication, centromere, repetitive sequences, telomeres?

what are centromeres?

binding sites of the kinetochore

what are telomeres?

regions at the end of a chromosome that aid in the stability of genetic material

what are repetitive sequences?

sequences of DNA that don’t code for specific genes, often a tandem sequence and account for 59% of the human genome

what types of sequences are considered unique?

protein coding genes, introns

roughly how many times does a moderately repetitive sequence appear in the genome

a few hundred to several thousand times

how many times will a highly repetitive sequence appear?

tens of thousands to millions of times

what are nucleosomes?

DNA wrapped around histone proteins, the structural unit of chromatin

what is chromatin?

the DNA protein complex that makes up a chromosome

what is a histone?

a protein group that DNA wraps around

what are the four histone proteins?

H2A, H2B, H3, H4

how do histones and DNA stay bonded to each other?

the lysine and arginine in the histones is positively charged with the DNA is negatively charged, binding them to each others

what is euchromatin?

loosely packed chromatin that can be transcribed

what is heterochromatin?

densely packed chromatin that cannot be transcribed

what is acetylation?

an acetylene group attached to an amino acid, nitrating the charge and separating the DNA from the histone so it can be transcribed

what does histone acetylation create?

euchromatin

what is DNA methylation

addition of a methyl group makes the nucleosomes tighten

what are the features of DNA that allow it to be replicate?

consistant base pairing and structure

what is the conservative model of replication

when the result is one entirely new set and one parent set

what is the semiconservative model?

one all new strand and one original parent strand

what is the dispersive model of replication?

both strands are a mix of old and new DNA

describe the set up of the Meselson and Stahl experiment

bacterial were culturerd in 15N forming heavy DNA, the 14N, meaning it replicated with lighter nitrogen, DNA was centrifuged and analyzed

what was the results of the first replication for the Measelson and Stahl experiment?

a band of DNA in the middle of the test tube

what models of replication did the first replication results leave as options?

semi-conservative and dispersive

what was the results of the second replication is the measles and stahl experiment

an additional band of lighter wight DNA formed above the miid-weight band

what did the results of the Measleston Stahl experiment prove?

the semiconservative model of replication

what is GATC methylation site?

sites that regulation DNA replication in bacteria

what are DnaA boxes?

locations for the binding of DnaA protein helping strands separate

what happens at AT-Rich regions

DNA strands separate

what is the oriC

origin of replication in E.coli

describe initiation of replication in bacteria?

DAM enzyme methylates the GATC sites, allowing the replication to begin

DnaA proteins binds to the DnaA boxes seperating strands

DNA helices binds to the origin and creates a replication bubble

where does initiation of replication occur in Eukaryotes?

several autonomously replicating sequences located in nucleosome free region

what is the role of Helicase

to unzip the two strands opening for the fork

what is the role of DNA Gyrase in replication?

nic’s DNA upstream of the fork to prevent supercoiling

what is the role of single-stranded binding proteins in replication?

to prevent bones from being reformed between complimentary nucleotides

what is the role of primase?

adds an RNA primer to unzipped DNA, creating a two-stranded section that that the polymerase can work on

what is the role of DNA polymerase III in replication?

adding nucleotides forming the next strand of DNA in the 5’-3’ direction