Biology CH 10 DNA RNA and the Genetic Code

What is DNA?

Deoxyribonucleic acid — the molecule that carries genetic information.

Where is DNA found?

In the nucleus of eukaryotic cells.

What is the structure of DNA?

A double helix made of two antiparallel strands.

What are the building blocks of DNA?

Nucleotides.

What are the three parts of a DNA nucleotide?

Phosphate group, deoxyribose sugar, nitrogenous base.

What are the four bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), Guanine (G).

What is complementary base pairing?

A pairs with T, and C pairs with G.

What is DNA replication?

The process of copying DNA before cell division.

When does DNA replication occur?

During the S phase of interphase.

What enzyme unwinds DNA?

Helicase.

What enzyme builds the new DNA strand?

DNA polymerase.

Why is DNA replication described as semi-conservative?

Each new DNA molecule contains one original strand and one new strand.

What is RNA?

Ribonucleic acid — involved in protein synthesis.

How does RNA differ from DNA? (3 differences)

• Single stranded

• Ribose sugar

• Uses uracil instead of thymine

What are the four bases in RNA?

Adenine (A), Uracil (U), Cytosine (C), Guanine (G).

What is mRNA?

Messenger RNA — carries genetic code from DNA to ribosome.

What is tRNA?

Transfer RNA — brings amino acids to the ribosome.

What is rRNA?

Ribosomal RNA — makes up ribosomes.

What is transcription?

Copying DNA into mRNA in the nucleus.

What enzyme is involved in transcription?

RNA polymerase.

What is translation?

Using mRNA to build a protein at the ribosome.

Where does translation occur?

At the ribosome in the cytoplasm.

What is a codon?

A sequence of three bases on mRNA.

What does each codon code for?

One amino acid.

What is an anticodon?

A complementary three-base sequence on tRNA.

What does a start codon do?

Signals the beginning of protein synthesis.

vWhat does a stop codon do?

Signals the end of protein synthesis.

What is a mutation?

A change in the DNA sequence.

What can cause mutations?

Radiation, chemicals, or copying errors.

What effect can mutations have?

No effect, harmful, or beneficial.