DNA replication

What are the three parts of a DNA nucleotide?

Phosphate group, deoxyribose sugar, and nitrogen-containing base.

What sugar is found in DNA?

Deoxyribose.

What are the four nitrogen bases in DNA?

Adenine, thymine, guanine, and cytosine.

What does A stand for in DNA?

Adenine.

What does T stand for in DNA?

Thymine.

What does G stand for in DNA?

Guanine.

What does C stand for in DNA?

Cytosine.

What makes up the sides of the DNA ladder?

Alternating phosphate groups and deoxyribose sugars.

What makes up the rungs of the DNA ladder?

Complementary nitrogen base pairs.

What is the shape of DNA?

A double helix, resembling a twisted ladder.

What does antiparallel mean?

The two DNA strands run in opposite directions.

What is complementary base pairing?

A pairs with T, and G pairs with C.

What base pairs with adenine?

Thymine.

What base pairs with thymine?

Adenine.

What base pairs with guanine?

Cytosine.

What base pairs with cytosine?

Guanine.

How many hydrogen bonds connect A and T?

Two hydrogen bonds.

How many hydrogen bonds connect G and C?

Three hydrogen bonds.

What are hydrogen bonds responsible for in DNA?

Holding the two complementary DNA strands together.

What is DNA helicase?

An enzyme that unwinds DNA and separates its two strands.

What does DNA helicase do during replication?

Breaks hydrogen bonds between complementary nitrogen bases.

What happens first during DNA replication?

Hydrogen bonds break, allowing the DNA strands to separate.

What happens after DNA strands separate?

Free nucleotides attach to exposed complementary bases.

What happens after free nucleotides attach?

Hydrogen bonds form between complementary bases.

What is semi-conservative replication?

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

Why is DNA replication called semi-conservative?

Half of each new DNA molecule is conserved from the original DNA.

What rule guides DNA replication?

Complementary base pairing: A-T and G-C.

How does DNA replication help prevent mutations?

Original strands serve as templates for accurate complementary base pairing.

What is chromatin?

Loose, uncondensed DNA inside the nucleus.

During what phase does DNA replication occur?

S phase of interphase.

When does DNA condense into visible chromosomes?

During M phase (mitosis).

What are sister chromatids?

Identical copies of a replicated chromosome.

What structure holds sister chromatids together?

The centromere.

What are homologous chromosomes?

A pair of chromosomes containing the same types of genes, one inherited from each parent.

What is the Chargaff base-pair rule?

The amount of adenine equals thymine, and guanine equals cytosine.

What percentage of DNA bases must add up to?

100%.

If adenine is 30%, what percentage is thymine?

30%, because A pairs with T.

If guanine is 20%, what percentage is cytosine?

20%, because G pairs with C.