DNA Quiz

What does DNA stand for?

Deoxyribonucleic Acid

What is the primary function of DNA?

It serves as the basis of our inherited traits, making up our genes and chromosomes.

Where is DNA located in human cells?

Mostly in the cell nucleus, with a small amount also found in other organelles (like mitochondria).

Why is DNA more chemically stable and less prone to mutation/breakdown than RNA?

DNA contains deoxyribose sugar, which has one less oxygen atom than ribose sugar.

How much DNA do humans share with one another?

About 99.9% of human DNA is identical between individuals.

What does the 0.1% difference in human DNA contribute to?

It contributes to differences between individuals, such as hair color, eye color, height, and other inherited traits.

What is the double helix structure of DNA compared to?

A twisted ladder.

What three components make up a single nucleotide building block?

1. Deoxyribose sugar (5-carbon sugar) 2. Phosphate group 3. Nitrogenous base

In the DNA ladder model, what forms the sides (backbone) and what forms the rungs?

Sides (Backbone): Alternating sugar and phosphate molecules. Rungs: Nitrogenous base pairs.

Name the four nitrogenous bases found in DNA.

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

What are the complementary base-pairing rules in DNA?

Adenine (A) pairs with Thymine (T) [A ↔ T] and Guanine (G) pairs with Cytosine (C) [G ↔ C].

Why do nitrogen bases pair specifically with each other?

Because the bases have complementary shapes and hydrogen-bonding sites that allow them to fit together properly.

How many hydrogen bonds form between Adenine and Thymine?

2 hydrogen bonds.

How many hydrogen bonds form between Guanine and Cytosine?

3 hydrogen bonds.

How does the double helix structure contribute to DNA stability?

The two strands are held securely together by hydrogen bonds between complementary base pairs, the bases fit together specifically, and the sugar-phosphate backbone provides structural support.

Explain the analogy connecting DNA, genes, and chromosomes to a book.

Chromosome = Book Gene = Chapter Nucleotides = Letters DNA = The language/code used to write the book

How many chromosomes do human body cells have, and where do they come from?

46 chromosomes total in most body cells (23 received from the mother, 23 from the father).

Where are chromosomes located inside a human cell?

In the nucleus of most human cells.

How is extremely long DNA packaged tightly to fit inside a cell?

DNA wraps around histone proteins to form nucleosomes, which fold and condense further to form chromosomes.

What is a gene and what does it do?

A short segment of DNA containing genetic instructions used to determine traits and provide instructions for making proteins.

Approximately how many genes do humans have?

Approximately 20,000 genes.

What constitutes the genetic code in DNA?

The specific order or sequence of nucleotides (bases: A, T, C, G) in DNA.

What is a mutation?

A change in the DNA sequence involving one or more nucleotides.

What is the central workflow connecting DNA to traits?

DNA (genes) → amino acid sequence → protein → cellular function / inherited trait.

What is a codon?

A group of three bases in the genetic code that corresponds to a specific amino acid (or a start/stop signal).

What determines the sequence of amino acids in a protein?

The sequence of bases in the DNA/gene.

What are three key functions of proteins in the body?

1. Structural components (muscles, skin, hair, bone parts) 2. Enzymes (control chemical reactions) 3. Hormones and functional cellular regulators