MODULE 6

Replication, storage of information, expression of information, variation by mutation

4 Characteristics of genetic material

Expression of the genetic information

Basis of the process of information flow within the cell

Information flow

Expression of the stored genetic information is the basis of what?

Genetic material

Source of variation among organisms through the mutation

Genetic variation

Raw material for the process of evolution

1868

When was DNA first discovered?

Friedrich Miescher

Isolated nuclei from white blood cells in pus on soiled bandages?

Nitrogen and phosphorus

In the nuclei, he discovered an unusual acidic substance containing what?

Nuclein

Miescher called nucleic acid what?

Archibald Garrod (1902)

First to provide evidence linking inherited disease and protein

Frederick Griffith (1928)

Took the first step in identifying DNA as the genetic material

Mice

What did Griffith use in his experiment?

Diploccus pneumoniae

What bacteria did Griffith use?

Type R

Diploccus pneumoniae that is rough in texture

Type S

Diploccus pneumoniae that is smooth and are enclosed in a polysaccharide capsule

Type R

Mice injected with this bacteria did not develop pneumonia, what type of diploccus pneumoniae bacteria?

Type S

mice injected with this type of diploccus pneumoniae bacteria developed pneumonia

Developed pneumonia

a mice was injected a mixture of heated type S and rough S diploccus pneumoniae bacteria, did the mice develop pneumonia or not?

Transformation

Conversion of one bacterial type into another

DNA

Transforming principle

yes

If protease was mixed with bacteria, would the bacteria be transormed?

no

If DNase was mixed with bacteria, would the bacteria be transformed?

Mouse dies

Type R + Killed type S + protease =

mouse lives

Type R + Killed type S + DNase =

Nucleotides

Building blocks of nucleic acids

Mononucleotides

Nucleotides are also called what?

Nitrogenous base, pentose sugar, phosphate group

3 essential components of nucleotides

Purines and pyrimidines

2 basic categories of nitrogenous bases

Purines

Nitrogenous base with two fused rings

Adenine and guanine

Types of purines

pyrimidines

Nitrogenous base with a single ring

Cytosine, thymine, uracil

Types of pyrimidines

Hydrogen bonds

Hold the base pairs together

2

How many hydrogen bonds join adenine and thymine?

3

How many hydrogen bonds link cytosine and guanine?

Scaffold protein

Form frameworks that guide DNA strands

Histones

DNA coils around protein structures called what?

Nucleosome

Bead part of DNA

Nucleosomes

Forms around packets of eight histone proteins

8

How many histones do nucleosomes form around?

30 nanometers

After a fifth type of histone anchors nucleosomes to short “linker” regions of DNA, how many diameters does the chromosome have?

Tetranucleotide (G-C-T-A)

Nucleotides linked together in the same order

Phosphate group, ribose, nitrogen-containing base

Nucleotide has 3 components:

Carbon, hydrogen, nitrogen, oxygen and phosphorus

Molecules making up a pyrimidines

Kilobase

Used to abbreviate a thousand

Megabase

Used to abbreviate million

Antiparallel

A double helix structure is what?

Right-handed double helix

Two long polynucleotide-chains are coiled around a central axis, forming what?

34 A or 3.4 nm

Each complete turn of the helix is how long?

10 bases

How many bases exist per turn in each chain?

20 A or 2.0 nm

The double helix measures how wide in diameter?

Antiparallelism

Opposing orientation of the 2 molecules chains in a DNA molecule

Bidirectional

Is DNA bidirectional or unidirectional?

DNA replication

Process by which the genome’s DNA isi copied in cells

Semiconservative replication

DNA is reproduced by what?

Semiconservative replication

process by which DNA replicates, where each new double-stranded DNA molecule is composed of one original strand and one newly synthesized strand

Conservative replication

Original parental DNA double helix remains intact, and a completely new double helix is synthesized alongside it

Dispersive replication

Original double helix is broken into fragments, and each new double helix is a mixture of old and new DNA segments

Conservative replication

One double helix specifying the creation of a second double helix

Dispersive replication

Double helix dispersed into two pieces that would join with newly synthesized DNA pieces to form two molecules

Matthew Meselson and Franklin Stahl (1958)

Pulished the result of an experiment providing strong evidence that semiconservative replication is the mode used by bacterial cells to produce new DNA molecules

Escherichia coli

What did Meselson and Stahl use to prove semiconservative replication?

S phase

When does DNA replication occur?

Helicase

Enzymes unwind and hold apart replicating DNA

Helicase

Opens up the DNA at the replication fork

Single-strand binding proteins

Coat the DNA around the replication fork to prevent rewinding of the DNA

Primase

Synthesizes RNA primers complementary to the DNA strand

DNA polymerase

Extends the primers, adding to the 3’ end, to make the bulk of the new DNA

DNA ligase

Gaps between the lagging strand are sealed by what?

Hydrogen bonds

What bond is formed during the leading strand?

Discontinuous

The lagging strands replication is what?

Okazaki fragments

What do you called the 150 nucleotides in the lagging strands?

Adenine and thymine (AT)

what is easier to separate?

DNA polymerase III

What adds new nucleotides to the exposed DNA strand?

Primer

What do you add to start replication?

Primer

Short sequence of RNA with a free 3’ end synthesized by the enzyme primase

DNA polymerase I

what removes the primer?

Elizabeth Blackburn and Carol Greider

Who discovered telomerase?

5’-TTGGG-3’

The tail of a telomerase has what repeating sequence?

3’ end of the G-rich strand

Capable of adding several more repeats of TTGGG nucleotide sequence to what end?

The longer life span

The longer the telomeres…

Senescence

State in which cell division ceases and the cell undergoes metabolic changes that cause it to function less efficiently

Polypeptides

One or more long chains of amino acids

Peptide

Short sequence of amino acids

Peptide bonds

Bonds that join amino acids

Muscle contraction

Actin, myoisn, dystrophin

Immunity

Antibodies, antigen, cytokines

Digestion

Carbohydrases, lipases, proteases, nucleases

Casein

Milk protein

Connective tissue

Collagen, elastin, fibrilin

Blood cell formation

Colony-stimulating factors, erythropoeitin

Dna & rna polymerase

Dna replication, gene replication

Ferritin

Iron transport

Blood clotting

Fibrin, thrombin

Cell division

Growth factors, kinases, cyclins

Oxygen transport

Hemoglobin, myogoblin

Blood sugar level

Insulin, glucagon

Keratin

Hair structure

Cell movements

Tubulin, actin

Cancer prevention

Tumor suppressors