BIO101 UNIT 4 - MEGAN CRAWFORD

Viruses force cells to make

more viruses

Virus structure

DNA surrounded by a protein coat

DNA

•Stores the hereditary information of a cell •Genes are discrete units of hereditary information consisting of a specific nucleotide sequence •Genes code to make a protein

percentage of A is equal to

T

percentage of T is equal to

A

percentage of C is equal to

G

percentage of G is equal to

C

Humans have what percentage of A

30%

Monomers of Nucleic Acids

Nucleotides

Polymers of Nucleic Acids

DNA: Deoxyribonucleic acid & RNA: Ribonucleic acid

RNA

assists in protein production

single stranded nucleic acid that passes along genetic messages

Nucleotide structure

Phosphate group 5-carbon sugar [pentose]

Nucleotide bases

Carbon rings that also contain nitrogen

Pyrimidines

Cytosine [1 carbon rings]

Thymine (DNA only) [1 carbon rings]

Uracil (RNA only) [1 carbon rings]

Purines

Adenine [2 carbon rings]

Guanine [2 carbon rings]

Complementary Base pairings T: U: C:

A [2 hydrogen bond] A [2 hydrogen bond] G [3 hydrogen bond]

The carbon double bonded to oxygen (the carbonyl group) is

#1

To form a carbon ring

a covalent bond forms between the hydroxyl group on the 4th carbon and the carbonyl on the 1st carbon

Nucleoside

"sugar + base

dehydration reaction between nitrogenous base and the 1'C of pentose links the base to the sugar"

phosphate group on a nucleoside creates

nucleotide

nucleotide

monomer of DNA & RNA

how do polynucleotides monomers link together

"Dehydration reaction between phosphate group and the hydroxyl on the '3 carbon"

DNA structures

"Two strands of polynucleotides complimentary bases pair between the two strand

Double helix anti-parallel [5'->3']"

RNA structure

single polynucleotide strand Bases in one part can bond to complimentary bases to other part can create complex structures

DNA VS RNA

DNA Double stranded Found in nucleus A,G,C,T Sugar=deoxyribose RNA Single strand found inside and out of the nucleus [cytoplasm] A,G,C,U sugar=ribose

DNA replication

DNA makes a copy of itself for cell division [nucleus]

Begins at the origin of replication and separate the two strands DNA replication

occurs in opposite directions and makes the bubble bigger until it copies the chromosomes

DNA begins to unzip at the replication fork

DNA Transcription

DNA creates messenger RNA [nucleus]

RNA translation

RNA is translated to produce a protein [cytoplasm]

What model does DNA use to replicate

semiconservative model

Conservative model

Two old strands stay together, two new strand pair

Semiconservative Model

Each new double helix contains one original and one new strand [in nucleus]Copies entire strand Occurs before cell division50 nucleotides/second

"Meselson and Stahl's experiment"

Bacteria + 15N [heavier] Bacteria transferred to media with 14N [light] [less dense than the first one] DNA = centrifuged [1x] DNA = centrifuged [2x]

Origins of Replication

Replication begins at a specific site with an specific sequence of nucleotide

replication fork

a Y-shaped point that where the two strands of a DNA separate so that the DNA molecule can be replicated

Bacteria vs Eukaryotes replication

Bacteria - One large Chromosome Eukaryotes - multiple, linear, and larger chromosomes. Has multiple sites of replication; bubbles begin to merge

Helicase

enzyme [protein] that unzips the DNA at the replication fork

Single Stranded Binding Proteins [SSBPs]

stabilizing the new single strands, prevent repairing

Topoisomerase

protein that breaks, swivels, and rejoins the parental DNA ahead of the replication fork

Primase

creates and places primers

primer

short segment of DNA that acts as the starting point for a new strand

DNA polymerases

enzyme that add nucleotides to existing chain [DNA]

DNA polymerase III

adds complementary nucleotides to the template strand

DNA polymerase III can only add new nucleotides to what end of a DNA strand

"the 3' end"

DNA builds in

"5' - 3' direction"

DNA reads from

"3' - 5'"

Leading strand

The new continuous complementary DNA strand synthesized while the replication fork progresses

Lagging strand

"DPIII moves away from the replication fork in a 5' to 3' direction to synthesize a new complementary strand"

Okazaki Fragments

Small DNA segments produced on the lagging strand

what does primase make for each okazaki fragment

RNA primer

what causes the extension of complementary strand

DNA polymerase III extends the CS from the primer until it reaches the former primer and Okazaki fragment

DNA polymerase I

Replaces the DNA polymerase III after it falls off from extension. Removes the RNA primer and replaces it will new DNA nucleotides

DNA ligase

catalyzes the covalent bond between the two Okazaki fragments

Gene Expression

Process where DNA directs the synthesis of proteins or just RNA

DNA is ____ into RNA

transcribed

Transcription

makes an mRNA from DNA [Initiation, Elongation, Termination]

occurs in the nucleus creates mRNA from a DNA template for one gene only one of the two strands is used as the template for the mRNA

RNA is ______ into Protein

Translated

Translation

creates polypeptide using the genetic information in an mRNA molecule [nucleotides -> amino acids]

Are DNA and Ribosomes in the same place

NO

What bases does DNA use

A, G, C, T

What bases does RNA use

A, G, C, and U

"During transcription, what does RNA 'U' pair with"

"DNA 'A'"

mRNA [messenger RNA]

"carries the genetic information to the ribosome 5' to 3'antiparallel to template strand"

non-template strand [coding strand]

the strand of DNA that is not transcribed into RNA during transcription

Central Dogma of Biology

DNA -> RNA -> Protein

initiation [Transcription]

Transcription factors [protein] bind to the DNA first. RNA polymerase forms a complex with the transcription factors [transcription initiation complex]

elongation [transcription]

"RNA polymerase untwist DNA, exposing about 10-20 nucleotides at a time.

RNA nucleotides complementary to DNA template are added to the 3' end"

Termination [transcription]

RNA polymerase passes through a specific sequence with a signal [AAUAAA]. 10-35 nucleotides downstream of the signal associated with the new pre-mRNA cut it free

TATA box

promoters contain a sequence, TATAAAA, to which transcription factors bind in order to establish the initiation complex

start point

site where transcription actually begins

template strand

the strand of DNA that specifies the complementary mRNA molecule

RNA polymerase

links ribonucleotides into a growing RNA chain during transcription

promotor

A region of DNA with a specific sequence that tells RNA polymerase where to begin transcription.

transcription unit

The stretch of DNA that is transcribed into RNA

The direction of transcription

downstream

the direction opposite of transcription

upstream

Transcription factors

A regulatory protein that binds to DNA and affects transcription of specific genes.

Transcription initiation complex

The completed assembly of transcription factors and RNA polymerase bound to a promoter.

terminator sequences

Sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing

Pre-mRNA

newly made mRNA before 5' cap, poly A tail, and splicing

primary transcript

initial RNA transcript from any gene before it is processed.

Ex: pre-mRNA

RNA processing

"extensive processing that alters both ends of the RNA and cuts sequences out of the middle

The 5' end of the pre-mRNA receives a 5' cap

50-250 nucleotides [poly-A tail] added to 3' end"

"Chargaff's rule"

A=T and C=G

Watson & Crick model

Double-helix structure of DNA

"Rosalind Franklin's contribution"

X-ray diffraction to get information about the structure of the DNA molecule

base pair rule

A =T & G =C

every species have different amount of A,T, etc

Nitrogenous Base

Cytosine, Guanine, Adenine, Thymine [DNA], Uracil [RNA]

Deoxyribose

penta sugar in DNA

polynucleotides

polymers of nucleotides monomers in a chain

untranslated regions

region of RNA that are not translated

introns [intervening sequences]

noncoding regions of nucleotides that lie between coding regions

exons

regions of nucleotides that are expressed

RNA splicing

introns are cut out of the pre-mRNA [primary transcript]

spliceosome

large complex of RNA that splices mRNA by interacting with ends of an RNA intron, releasing the intron, and joining the two adjacent exon

Alternate RNA splicing

creates different mRNA molecules from the same primary transcript

Functional domains

descrete structural and functional region

ex: dna binding domain, active site for an enzyme

how many nucleotides to produce 20 amino acids

combination of 3 nucleotides produce 64 possible arrangements = enough to generate 20 amino acids

triplet code

set of three-nucleotides-long words specify the amino acids for polypeptide chains

codons

mRNA nucleotide triplets

what are synthetic mRNA used to discovered

genetic code

AUG codes for

methionine [start codon]