Human Biology: Unit 2 Exam

Explain the difference between a genotype and a phenotype.

A genotype is an organism’s internal genetic code, whereas a phenotype is the observable physical expression of that code.

What molecule is the “blue print” or “recipe” for building all the proteins in your body?

DNA (deoxyribonucleic acid).

Where is DNA located in the cell?

Mainly in the nucleus of a cell, but also in the mitochondria.

Can DNA leave the nucleus in a cell?

No, they are too large and cannot fit through any pores to leave.

What are the base pairing rules that link the two strands of DNA together?

• A always pairs with T via 2 Hydrogen bonds

• C always pairs with G via 3 Hydrogen bonds

Describe at least 3 general roles that proteins serve in your cells.

1. Cellular structure: provides physical framework and support to cells and tissues.

2. Metabolic processes: act as enzymes to speed up necessary chemical reactions in the cell.

3. Molecular transport: facilitate the movement of nutrients and molecules across cell membranes or through the bloodstream.

Why do new proteins need to be made?

Existing proteins break down over time and cannot last forever.

What is messenger RNA (mRNA)?

mRNA is a single-stranded molecule that copies genetic instructions from DNA and carries them to the cytoplasm.

Describe the role mRNA plays in protein synthesis.

mRNA serves as a template for the ribosomes to synthesize proteins.

Describe how mRNA is synthesized. What enzyme(s) handle this process?

mRNA is synthesized through a process called transcription, where a specific segment of DNA is copied into a single-stranded DNA molecule. RNA polymerase is responsible for mRNA synthesis.

Where in the cell does mRNA synthesis happen?

In the cell nucleus in eukaryotes, and in the cytoplasm in prokaryotes.