Chapter 14- DNA: Genetic Material Flashcards by Chloe LaVertu

Frederick Griffith

Studied Streptococcus pneu.

How well did you know this?

Not at all

Perfectly

S strain (virulent)

Killed the mice

How well did you know this?

Not at all

Perfectly

R strain (non-virulent)

Did not kill mice

How well did you know this?

Not at all

Perfectly

Chromosomes

Composed of chromatin

How well did you know this?

Not at all

Perfectly

Chromatin

40% DNA, 60% protein

How well did you know this?

Not at all

Perfectly

DNA is a ____ ____ and is composed of ____

Nucleic acid, nucleotides

How well did you know this?

Not at all

Perfectly

Deoxyribose

5-carbon sugar

How well did you know this?

Not at all

Perfectly

Phosphate Group

Attached to 5’ carbon of sugar

How well did you know this?

Not at all

Perfectly

Nitrogenous bases

Adenine, thymine, cytosine, guanine

How well did you know this?

Not at all

Perfectly

Free hydroxyl group (-OH)

Attached at the 3’ carbon of sugar

How well did you know this?

Not at all

Perfectly

Phosphodiester bond

Bond between adjacent nucleotides

How well did you know this?

Not at all

Perfectly

Phosphodiester bond formed between

Phosphate group of one nucleotide and 3’ of next nucleotide

How well did you know this?

Not at all

Perfectly

Amount of adenine=

Amount of thyamine

How well did you know this?

Not at all

Perfectly

Amount of cytosine=

Amount of guanine

How well did you know this?

Not at all

Perfectly

Maurice Wilkins

Purified DNA, X-ray diffraction

How well did you know this?

Not at all

Perfectly

Rosalind Franklin

Discovered DNA is helical

How well did you know this?

Not at all

Perfectly

Watson and Crick

Stole research from other scientists to propose a double helix structure

How well did you know this?

Not at all

Perfectly

2 strands of DNA

Polymers of nucleotides

How well did you know this?

Not at all

Perfectly

Phosphodiester backbone

Repeating sugar and phosphate units joined by phos. bonds

How well did you know this?

Not at all

Perfectly

A forms ____ ____ ____ with T

2 hydrogen bonds

How well did you know this?

Not at all

Perfectly

G forms ____ ____ ____ with T

3 hydrogen bonds

How well did you know this?

Not at all

Perfectly

Requirements for DNA replication

Something to copy
Something to do the copying
Building blocks to make copy

How well did you know this?

Not at all

Perfectly

Something to copy

Parental DNA molecule

How well did you know this?

Not at all

Perfectly

Something to do the copying

Enzymes

How well did you know this?

Not at all

Perfectly

Building blocks to make copy

Nucleotide triphosphates

Initiation

Replication begins

Elongation

New strands of DNA synthesized by DNA polymerase

Termination

Replication is terminated

DNA polymerase I

Acts on lagging strand to remove primers and replace them with DNA

DNA polymerase II

Involved in DNA repair processes

DNA polymerase III

Main replication enzyme

DNA polymerase

Matches existing DNA bases with complementary nucleotides and links them

1st common feature of DNA polymerase

Add new bases to 3′ end of existing strands

2nd common feature of DNA polymerase

Synthesize in 5′-to-3′ direction

3rd common feature of DNA polymerase

Require a primer of RNA (Not required for RNA polymerase)

Prokaryotic

Single, circular molecule of DNA

Replicon

DNA controlled by an origin

Prokaryotic replication

Begins at one origin of replication (oriC), proceeds in both directions around the chromosome and ends at terminus

Unwinding DNA

Causes torsional strain

Helicases

Uses energy from ATP to unwind DNA

Single-strand-binding proteins

Coat strands to keep them apart

Topisomerase

Prevent supercoling

DNA gyrase

Used in replication

DNA polymearase can...

Only synthesize in 1 direction

Leading strand synthesized ____ from...

Continuously, from an initial primer

Lagging strand synthesized ____ with...

Discontinuosly, mutiple priming events

DNA primase

RNA polymerase that makes RNA primer (10-20 base pairs long)

Leading-strand synthesis

- Single priming event - Strand extended by DNA pol III

B subunit forms

Sliding clamp to keep it attached

Lagging strand synthesis

- Discontinuous synthesis - Backbone sealed - All RNA primers removed and replaced by DNA

Backbone sealed by

DNA ligase

Replisome

Enzymes involved in DNA replicatio for a macromolecular assembly

Primosome

Primase, helicase, accessory protiens

Complex of 2 DNA pol III

One strand for each

Eukaryotic replication complicated by

- Larger amount of DNA in multiple chromosomes - Linear structure

Requires ____ ____ ____ for dealing with ends only

new enzymatic activity

Mutiple replicons

Mutiple origins of replications for each new chromosome

Primase in ER

Includes both DNA and RNA polymerase

Clamp is called

Proliferating cell nuclear antigen

Initation phase of ER

Requires more factors to assemble both helicase and primase

Telomeres only found on ends of

Eukaryotic chromosomes

Telomeres

Protect ends of chromosomes from nucleases and maintain integrity of linear chromosomes

Chromosomes get ____ after each round of cell divison

Shorter

Telomeres composed of

Short repeated sequences of DNA

Telomerase

Enzyme makes telomere of lagging strand using an internal RNA template

Cancer cells show ____ of ____

Activation, telomerase

Errors in DNA due to ____

Replication

Mutagens

Any agent that increases the number of mutations above background level

Average number of erros per cell replication

3 to 4

Specific repair

Targets a single kind of lesion in DNA and repairs only that damage

Nonspecific repair

Uses a single mechanism to repair mutiple kinds of lesions in DNA

Photorepair

For one particular form of damgae caused by UV light

Thymine dimers

Covelant link of adjacent thymine bases in DNA

Photolyase

Absorbs light in visible range

Excision repair

1. Recognition of damage 2. Removal of the damaged region