Unit 4

DNA RNA Proteins

DNA/ RNA/ Proteins Word Meanings

• Deoxy- a molecule containing less oxygen than another

• ribose- A pentose sugar, C5H10O5

• Complementary– to “match up”

• Subunit– a piece or small part of a larger unit.

• replication – the act of duplicating, copying, or reproducing

• transcription– the act or process of rewriting in a different script.

• translation– to rewrite in a second language having the same meaning as the original

source.

I. DNA: Deoxyribonucleic Acidi. Complete instructions for manufacturing all the

proteins for an organism. (which determine all your other characteristics)

ii. The “recipe” for life!iii. structure of DNA proved that it was in fact the

molecule of heredity iv. Analogy:1000 textbooks= all the info (DNA/genes) of

1 single organism

a. Structurei. Watson & Crick

1. proposed that DNA is made of chains2. nucleotides held together by nitrogenous bases

(teeth of zipper)3. proposed that DNA is shaped like a long zipper that is

twisted into a coil like a spring → helix4. DNA is a double helix

The Base pairing rules: (A binds to T and G binds to C).

II. Replicationa. Helicase unzips the

double helix, forming replication forks.

b. DNA polymerase is an enzyme that joins individual nucleotides to produce a new strand of DNA.

c. New bases are added, base pairing rules: (A with T and G with C).

d. This is a Semi-Conservative process = One old strand of DNA with one new strand of DNA

DNA→DNA

III. Mutationsi. Any changes in the DNA

sequencesii. This could be:

1. Deletion of bases2. Duplicating bases3. Ceratain bases changing

places4. New bases being inserted

where they do not belong.

iii. Mutations can result in:a. Genetic diseasesb. Cancerc. New genetic traitsd. No harm at all

• Genetic Disorders caused by mutations to the DNA:Disorder Mutation Chromosome

Color blindness Point XCri du chat Deletion 5Cystic fibrosis Point 7Down syndrome Extra Chromosome 21 21

Duchenne muscular dystrophy

Deletion X

Haemochromatosis Point 6Haemophilia Point XKlinefelter syndrome Extra X-Chromosome (males) XSickle-cell disease Point 11Tay–Sachs disease Point 15Turner syndrome Missing one X-Chromosome X

IV. Manipulating DNA– How do we manipulate DNA?

• We can literally cut the DNA into pieces.– This is done through the use of proteins known as restriction

enzymes– They cut the DNA at certain Base Pair sequences

– We use the cut up DNA for all sorts of things.

• Paternity Test and Criminal Investigations– Cut up fragments of certain DNA segments are put

into a gel electrophoresis.– Depending on how big the segment of DNA, the

further down the gel a fragment of DNA will move.– Doctors and scientist can then compare one

persons DNA to another persons to see if they’re related.

• Genetic Engineering– Cut up fragments of DNA segments with specific genes can

be added to the DNA of a fertilized egg.• This can give rise to organisms with new traits.• Ex. Mice that can glow

Here the gene for insulin is being put into the plasmid of a bacterial cell.The bacteria will now produce insulin for human use.

• Cloning– Theoretically, any organism can be cloned to make a

genetically identical organism.

– This is done by a process called Nuclear Transfer1. Extract the nucleus of an unfertilized egg.

2. Insert a nucleus (DNA) from a cell of the organism you want to clone.

3. Cause the egg cell with the novel nucleus to start dividing by stimulating the egg with a shock of electricity.

4. After the embryo grows for a few days it is placed inside a serogate mother and allowed to develop there until birth.

These two cats are clones: But they look different. This is because different genes on the same DNA can be activated by the different environments the organism grew up in.

V. RNAa. Ribonucleic Acidb. Single strandedc. RNA is a special copy of DNA used to make proteins.

Single RNA strand

a. RNA Nucleotides (monomer)i. Subunit of RNAii. 3 parts:

1. phosphate group2. simple sugar= ribose3. nitrogenous base

a. U= uracil (Replaces T)b. A= adeninec. G= guanined. C=cytosine

Complementary base pairs → A-U & C-G

b. Transcription (DNA→RNA)i. Creating RNA from DNA

1. RNA polymerase is an enzyme that 1. uses only one side of DNA (one DNA strand) to create a single strand

of RNA.2. Uses DNA as a template to lay RNA nucleotides in a specific order

according to the DNA code.

2. New bases are added according to the base pairing rules: (A with U, G with C, T with A).Ex. DNA = ATTCGCATT RNA = UAAGCGUAA

c. 3 Types of RNAi. mRNA → messenger

carries a copy of the DNA’s instructions (code) for the creation of proteins.

ii. rRNA → ribosomal Makes up ribosomes - structures where proteins

are assembled.

iii. tRNA → transfer carries amino acids to the ribosome and

matches them to the coded mRNA message.

d. Translation (mRNA → proteins)

i. Converting mRNA into amino acids then into a protein

1. To begin Translation the rRNA must binds to the mRNA

2. translation begins at the start codon[AUG]-(three bases in a row) on the mRNA.

3. tRNA contains an anti-codon that binds to the mRNA’s codon and carries one kind of amino acid.

4. The amino acids bond together and stop when a “stop codon” is reached.

5. The newly formed polypeptide (protein) is then released.

e. Amino Acidsi. Basic building blocks of proteins carried by tRNAii. Codon: 3 bases on mRNA code for 1 amino acidiii. 64 different combinations can create 20 different

amino acids.

What does a Protein look like?

Transcription Replication

RNA polymerase used DNA polymerase used

RNA nucleotides linked(A U C G)

DNA nucleotides linked(A T C G)

A single stranded RNA molecule is made

A double stranded DNA molecule is made

Only 1 DNA strand is used as a template.

Both DNA strands get replicated.

DNA-RNA Differences

DNA→RNA DNA→DNA