Biology Chapter 10 - DNA, RNA, and Protein Synthesis

DNA structure

Double helix composed of paired nucleotides (sugar, phosphate, nitrogen base); "ladder rungs"

Complementary base pairing

Connected by hydrogen bonds; A-T and C-G

Replication fork

The points at which the DNA strands separate during replication

Purines

Bases with two rings of carbon and nitrogen atoms; Adenine and Guanine

Pyrimidines

Bases that have one ring of carbon and nitrogen atoms; Cytosine and Thymine

DNA replication

The two nucleotide chains separate by unwinding and each chain serves as a template for a new nucleotide chain

Types of RNA

Messenger RNA (mRNA); transfer RNA (tRNA); ribosomal RNA (rRNA)

Messenger RNA

RNA nucleotides in the the form of a single uncoiled chain; carries genetic information from the DNA in the nucleus to the cytosol of a eukaryotic cell

Transfer RNA

Single chain of about 80 RNA nucleotides folded into a hairpin shape that binds to specific amino acids; about 45 varieties of it

Ribosomal RNA

Most abundant form of RNA; consists of RNA nucleotides in a globular form; makes up ribosomes, where proteins are made

RNA structure

Ribose; Uracil replaces Thymine; single strand

Transcription

Process by which genetic information is copied from DNA to RNA; done in the nucleus

Translation

The process of converting the genetic code in RNA into the amino acid sequence that makes up a protein; done at the ribosome

RNA polymerase

Primary transcription enzyme; synthesizes RNA copies of specific sequences of DNA; initiates RNA transcription by binding specific regions of DNA; promoters

Termination signal

Specific sequence of nucleotides that marks the end of a gene; at this, RNA polymerase releases both the DNA molecule and the newly formed RNA molecule

Protein synthesis

Production of proteins

Genetic code

A correlation between a nucleotide sequence and an amino acid sequence used by organisms to translate mRNA transcripts into proteins

Codon

Each combination of three mRNA nucleotides

Start codon

AUG; starts translating mRNA molecule

Stop codon

UAA, UAG, and UGA; cause ribosome to stop translating mRNA

Anticodon

Sequence of three nucleotides; each codon is paired with this; found in tRNA

Adenine

Nitrogen base purine with 2 rings; pairs with T

Guanine

Nitrogen base purine with 2 rings; pairs with C

Thymine

Nitrogen base pyrimidine with 1 ring; pairs with A

Cytosine

Nitrogen base pyrimidine with 1 ring; pairs with G

Base-pairing rule

The rule stating that, in DNA, Cytosine pairs with Guanine and Adenine pairs with Thymine (or with Uracil in RNA)

Deoxyribose

The sugar molecule in a DNA nucleotide

Ribose

The sugar molecule in a RNA nucleotide

DNA polymerase

An enzyme that binds to the separated strands of DNA; assembles each strand's complement in replication

Double helix

The shape of a DNA strand

Mutation

A change in DNA; may or may not be visible; may or may not be harmful

Promoter

A nucleotide sequence on a DNA molecule that, when attached to an RNA polymerase molecule, will initiate transcription of a specific structural gene

Watson and Crick

American scientists who helped find the structure of DNA; won the Nobel prize

Franklin and Wilkins

English scientists who produced an x-ray of DNA and majorly helped find the structure of DNA; won the Nobel prize

Hydrogen bonds

What connects the base pairs in DNA?

S phase

When does DNA replication occur?

Step 1 of DNA replication

The enzyme helicase separates the strands of DNA

Step 2 of DNA replication

The DNA helicase "unzips" the two complementary chains

Step 3 of DNA replication

Enzymes called DNA polymerases attach new complementary nucleotides to each strand

Semi-conservative replication

When the old strands of DNA are still found in the replications

Cytoplasm

Where does transcription occur?

Step 1 of transcription

RNA polymerase binds to a promoter

Step 2 of transcription

Promoters mark the starting point of a gene

Step 3 of transcription

DNA unwinds

Step 4 of transcription

RNA polymerase adds one RNA nucleotide complement to the DNA at a time

Step 5 of transcription

It all stops when the RNA polymerase reaches its termination signal

Peptide bonds

What type of bonds hold amino acids together in polypeptides?

Ribosome

Where does translation occur?

Step 1 of translation

tRNA joins with an anticodon

Step 2 of translation

The anticodon reads the complementary base pairs on the mRNA

Step 3 of translation

The anticodon transports free amino acids to the tRNA to form the protein

Step 4 of translation

When complete, everything goes back to free floating

Human genome

The entire gene sequence of a human

3.2 billion

How many base pairs are in the human 23 chromosomes?

30,000

How many genes do humans have?

Five-carbon sugar, nitrogen base, and phosphate group

What are the three things that make up a nucleotide?

Evolution

What would a good mutation result in?

Diseases; cancer; defects

What would a bad mutation result in?

Yes

Does production of DNA and RNA happen at many places along the strands for each?