Shani B.Chapter 7 part 1 Replication

1 condon=

1 amino acid ("Genetic Code")

What is a triphosphate deoxyribonucleotides?

A nucleotide with 3 phosphates

What is a primer?

A piece of RNA that has a free 3' OH group; starts the new copy of DNA (nucleotides will be added to this)

Are Plasmids naturally occurring or man-made?

Both

How is DNA made?

By linking nucleotides together via anabolism.

Genomes of prokaryotes are packaged in what 2 structures?

Chromosomes & plasmids

Eukaryotic Genomes

Chromosomes Pictures with microscope

What is DNA Replication?

Copying DNA

All cells and some viruses use _____as genome?

DNA

What is a chromosome?

DNA + protein and RNA

Step 7 Replication: What links Okazaki fragments together?

DNA ligase (phoshodiester bonds)

Triphosphate deoxyribonucleotides

DNA replication---> Nucleotides are ALWAYS added to the 3' end

What is a nucleosome?

DNA wrapped around histone proteins

What is the Central Dogma of Genetics?

DNA--transcription-->RNA--translation-->Proteins "cookbook"-->Chef-->cookies (ribosomes)

How many chromosomes do most eukaryotes have?

Most have more than one

How many chromosomes do bacteria have?

Most have only one chromosome (a few have 2)

What does DNA synthesis require?

Nucleotides & energy

What are the fragments called?

Okazaki fragments

How many origins of replication do bacterial chromosomes have?

Only have 1.

what is an ori?

Origin of replication-->nucleotide sequence that tells the enzymes where to start copying

Where is extranuclear DNA found in eukaryotic cells?

Outside the nucleus and within mitochondria and chloroplasts. And within plasmids.

RNA viruses use_____as genome

RNA

...

Synthesis of lagging strand

Eukaryotic Genomes

These chromosomes exist in _____?

What do SSBP do?

They bind to protect and stabilize ssDNA

What do chromosomes do during cell division (mitosis)?

They condense-->Now thick enough to be seen with a light microscope.

How many hydrogen bonds do guanine and cytosine have?

This is complimentary base pairing permits the precise replication of DNA Guanine & Cytosine (3 hydrogen bonds)

What converts codons of genes to amino acids?

Transcription & translation

Triphosphate deoxyribonucleotides

What is required to make DNA?

What are the bases in a nucleic acid polymer?

adenine, thymine (DNA only), guanine, cytosine, uracil (RNA only)

STEP 3 Replication: What does primase do?

an RNA plymerase, adds a primer using complementary base pairing. 5'-->3' (enzyme that builds a primer) RESULTS in creating a short double-stranded nucleic acid region with a free 3' OH

the two strands run ______to one another

antiparellel 5'-->3' and 3'-->5'

The "lagging strand" replication moves ____the replication fork and occurs in fragments

away

What can Primase do that DNA polymerase cannot?

can bind to ssDNA

What are chromatin fibers?

clumps of nucleosomes + more proteins

What is a bacteriocin plasmid?

contains gene for bacteriocin, a protein that kills similar type cells that don't have this plasmid.

What is a virulence plasmid?

contains genes for structures, toxins, enzymes etc. that enable a pathogen to be virulent (disease-causing)

What is DNA replication?

copying DNA; using existing DNA molecule to make a new one. Allows a cell to pass on genome to progeny cells

What are the triphosphate deoxyribonucleotides?

dGTP, dATP, dTTP, dCTP

In a nucleic acid polymer: What is the sugar unit of DNA? RNA?

deoxyribose, ribose

DNA exists as a _______

double helix

What does semiconservative mean?

each new DNA molecule contains one old strand and one new strand.

What is a resistance plasmid?

have genes that make the bacterium resistant to antibiotics, toxins, heavy metals, etc.

What enzymes are used for DNA replication?

helicase, primase, DNA polymerase, & gyrase

Step 4 Replication: what do dTTP, dATP, dCTP, dGTP do?

hydrogen bond to template strand

Where are they found?

in the nucleus

What shape are chromosomes?

linear

What is DNA ligase?

makes a phosphodiester bond between Okazaki fragments (chunks of DNA)

Step 5 Replication: DNA polymerase binds, what does it do?

makes covalent bonds between nucleotides (500-1000 nucleotides per second)

How many origins of replication do eukaryotic chromosomes have?

many

nucleic acid is usually "_______" in the cell with proteins

packaged (not naked DNA)

What is the structure of a nucleotide?

pentose (5-carbon) sugar + phosphate + a base

What type of bond is between the 5' C on one nucleotide and 3'C of the next that makes up the "sugar-phosphate backbone"

phosphodiester

Step 1 Replication: What happens at the origin of replication?

proteins used to package the DNA are removed

What does bacterial gyrase do?

relieves supercoiling

Step 6 Replication: What is DNA polymerase I?

removes RNA primers and replaces them with DNA.

What is a nucleic acid?

sequence of nucleotides bound together by phosphodiester bonds

What are SSBP?

single strand binding proteins

What is a plasmid?

small loop of DNA: can replicate independently of the chromosome

What is a codon?

specific sequence of 3 nucleotides

Define: gene

specific sequence of nucleotides that codes for a protein or RNA molecule

What are the "ingredients" for DNA Replication?

template strand, primer, triphosphate deoxyribonucleotides, enzymes, SSBP, & ori

What is a template strand?

the strand of a DNA molecule that will be copied

Describe Bacterial Chromosomes

they are circular ---> exists in folded loops held in place by protein and RNA

The "leading strand" replication moves ____the replication fork and is continuous

toward

What end are nucleotides always added?

3'

What direction does replication go in?

5'-->3'

Plasmids in Eukaryotic cells

Are present in some fungi and protozoa.

What type of bonds hold DNA together between bases?

Hydrogen bonds

What does bidirectional mean?

In bacteria, both strands are copied at the same time; two replication forks moving in opposite directions.

Step 2 Replication: What does the enzyme helicase do?

It "unzips" the DNA molecule (H-bonds between bases are broken)

What else does DNA polymerase do?

It can "proofread" --> fixes any mistakes in base pairing (only about 1 error per ten billion nucleotides)

What are some characteristics of DNA replication?

It is semiconservative, and bidirectional

Step 5: What is DNA polymerase III?

Links nucleotides (phosphodiester bonds)

What two structures are the genomes of eukaryotes packaged into?

1. chromosomes (in the nucleus) 2. Extra-nuclear DNA (outside the nucleus)

How many hydrogen bonds do Adenine and Thymine have?

Adenine & Thymine (2 hydrogen bonds)

Define: Genome

All of the genetic material of a cell

What are some types of plasmids?

Fertility plasmids, resistance plasmids, bacteriocin plasmids, and virulence plasmids

What is a fertility plasmid?

Have genes for bacterial conjugation--> transfer of genes from one bacterial cell to another via the sex pilus

Mitochondrial & chloroplast DNA

Have their own circular DNA. Contain genes for some proteins needed by the organelle.

What is an example of a eukaryotic plasmid?

Saccharomyces cerevisiae (brewer's yeast). Carries a large plasmid that only has genes for replication of the plasmid.

Why is the plasmid of Saccharomyces cerevisiae important?

used by scientists-->Recombinant DNA technology