Lecture 1 Flashcards by Mindy Ward

What was the chemical structure of a gene?

passed from cell to daughter cell mostly unchanged
undergoes accurate and unlimited replication
must direct development of a cell and the daily life of the cell

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the information- containing elements that determine the characteristics of a species

genes

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Chromosomes contain

DNA and protein

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building blocks of DNA

nucleic acids

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What is DNA made up of

polynucleotides have POLARITY
5' phosphoryl end
3' hydroxyl end
phasphate group, sugar group and a base... hooked together by hydroxly polariy linkage.
always 5-3 prime

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What has 2 long …. with 4 types of …. subunits

DNA has polynucleotide chains with nucleotide

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what is a nucleotide?

5-carbon sugar and nitrogenous base covalently linked via glycosidic bonds

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What is the sugar in DNA?

deoxyribose

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What are the 4 bases?

adenine, cytosine, guanine, and thymine

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What is the 3D structure of DNA?

double helix, 1 turn every 10 bp

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each strand’s sequence is complementary to partner

antiparallel, helps DNA function the way it does.. allows for replication

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Whare are the purines?

adenine and guanine

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What are pyrimidines?

cytosine and thymine

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What does adenine pair with?

thymine… 2 hydrogen bonds

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What does guanine pair with?

cytosine (3 hydrogen bonds)

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complete set of information in a an organims’s DNA

genome

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At replication, the entire genome must be

duplicated and passed to the daughter cell

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allow for the genome to be replicated

complimentary strands, each strand serves as the template

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Dna has Minor and major groves

….

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single long linear DNA molecular associated with proteins that fold and pack it into compact structre

chromosome

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autosomes and sex chromsomes

22 pairs and 2 sex

Each chromosome is a

single long linear DNA molecular associated with protiens that fold and pack it into compact structure

What information is found on chromosomes?

encoding proteins

encoding RNA molecules

Information that does not contain DNA in a chromosomes is for?

regulatory information

“Junk” DNA

2 copies are called

homologs

Little of genome is

protein coding

most DNA is

transposable elements lots of intonic sequences regulatory sequences

region of gene that codes for proteins

exons

typically 145 bp floating in sea of lg introns, the sequence of which is of little consequence

coding regions (exons)

sequences are relatively conserved during evolution

functional

sequences mutate randomly wo consequnces

non functional

not only do we share the same genes, but large blocks of

them are conserved in the same order on the chromosome "conserved synteny"

chomosomes are replicated; they are decondensed and ccant be easily distinguished

interphase

become highly condensed and separated into two duaghter nuclei

mitosis

where duplication of the DNA begins

DNA replication origin

allows one copy of each duplicated and condensed chromosmes to be pulled into each daughter cell when the cell divides

centromere

at the end of a chromsomes, contain repetitive sequences that enable the end to be efficiently replicated

telomere

must allow rapid localized access to DNA for gene expression

dynamic situation

DNA binding protines involved in forming chromosomes

histones and non-histone chromosomal proteins

Protein + nuclear DNA=

chromatin

most basic unit of chromosome packing

nucleosome

beads on a string

linker DNA and DNA wrapped around histones

nucleosome is made up of

histone octomer 8 histone protiens -2 molecules each of H2A, H2B, H3, H4 - And 2x stranded DNA that is 147 nucleotide pairs long

what break down DNA by cutting btw nucleosomes and degrading the exposed DNA btw nucelosome core particles?

nucleases

small proteins with common structural motif called histone fold

histones

What are N terminal amino acid tail that extends out from the core of nucleosome improtant for?

Covalent modifications important for chromatin regulation

interactions btw DNA and histone

142 H bonds are formed btw DNA and histone core in each nucleosome Hydrophobic interactions salt linkages histones are highly conserved; most changes would be lethal specialized variant histone proteins add to vaious possiblechromatin sturctures

lysine and arginine (positive charges) comprise more than 1/5 of histone residues; effectively neutralize negatively charged DNA backbone

salt linkages

Chromatin remodeling complexes

allow further loosening of DNA/ histone contact

proteins are related to....

helicases and are ATP dependent; bind to both protein core and DNA

stacking may be facilited by histone tails (esp H4) | H1 "linker histone" is present in 1:1 ratio with nucleosome cores

zig zag model... nucleosome packing- a dense fibrous structure w diameter of 30 nm

linker histone larger than other histone proteins- also less well conserved contacts both DNA and protein changes the path of the DNA as it exits the nucleosome

Histone H1