Genetics exam 1

What is genetics?

how traits are inherited and how they vary among individuals

what are epigenetics?

study of heritable phenotype changes that do NOT involve alterations in DNA sequence

what is phenotype?

the outward, physical characteristics of an individual organism

what is genotype?

specific genetic composition (DNA sequence)

what are forward genetics?

start with mutant phenotype → identify gene responsible

What is reverse genetics?

start with known gene → alter or mutate → analyze phenotype

flow of genetic info in cells

DNA → RNA → proteins

what is a gene?

sequence of DNA that code for proteins or functional RNA (noncoding RNA)

What is a chromatin?

contains genomic DNA that is observable in the nuclei of non dividing cells

what are chromosomes?

condensed chromatins that form discrete dark staining bodies before cell division

what are the key chemical differences between protein and DNA?

Proteins: do not contain phosphorus DNA: do not contain sulfur

During the Hershey-chase experiment, 32p got incorporated only into ____, and 35s only into _____

DNA; protein

Difference between DNA and RNA building blocks

different nitrogenous and sugar bases

How many chromosomes are in a human somatic cell?

23 pairs of different chromosomes

What are autosomes?

the other 22 pairs of chromosomes

purine nucleotides

A;G

Pyrimidine nucleotides

C;T

number of nucleotides are distinguished by what?

carbon atoms of sugars

What is Chargaff’s rule?

amount of A and T are roughly the same; same with C and G

Bases of opposite chains are paired with what?

hydrogen bonds

what is semiconservative replication?

original DNA strand acts as template for new DNA strand

what is conservative replication?

original DNA is conserved and new DNA is made up of newly synthesized strands

where do Okazaki fragments appear?

on the lagging strand

what is exonuclease proofreading?

cuts out wrong nucleotides so synthesis can proceed

what is telomerase?

helps avoid shortening of chromosomes

where does eukaryotic MRNA synthesis occur?

nucleus

what happens to MRNA 5’ end?

capped

what is the function of capping and polyadenylation?

stability and transcriptibility

what happens to 3’ MRNA end?

polyadenylated

why does RNA polymerase not need any primer but DNA polymerase does?

unlike DNA, RNA does not permanently store genetic information in cells.

what % of genes have introns and exons?

90%

are introns or exons longer?

introns

what is the transcriptional unit?

transcribed region of DNA

Levels of regulation of gene expression

transcriptional level ; postranscriptional level; translational level; post translational level

what are cis-acting factors?

presence of DNA

what are trans-acting factors?

presence of typically proteins but sometimes RNA

what is a relaxed chromatin structure called?

euchromatin

what is a condensed chromatin structure called?

heterochromatin

what leads to a condensed chromatin

DNA methylation; histone deacetlyation

what leads to an open chromatin?

DNA demethylation ; histone acetylation

controlling the expression of eukaryotic genes requires what?

transcription factors

general transcription factor are required for?

transcription initiation

what do specific transcription factors do?

increase transcription in certain cells or in response to signals

what is Griffith’s experiment?

genetic material could be transferred between dead bacteria and living bacteria

shown with pneumonia in mice

What is the Hershey-chase experiment?

Used radioactive material to label DNA and protein; infected bacteria passed on DNA; proved DNA is genetic materials not proteins

what is a nucleobase?

nitrogenous base

what is a nucleoside?

nitrogenous base, pentose

what is a nucleotide?

nucleoside, phosphate

dna polymerase adds nucleotides to what end

3’

how long are Okazaki fragments?

1000/2000 nucleotides long

Telomerase disease?

Werner syndrome