Biology: Page 7

Flashcards generated from lecture notes on DNA and protein synthesis.

What discovery are James Watson and Francis Crick credited with?

They discovered that DNA has a double helix shape.

What does DNA stand for?

Deoxyribonucleic Acid

What is the shape of DNA?

Double Helix

Describe the structure of DNA.

DNA resides in chromosomes, which are condensed within histone proteins. Unfurling these histones reveals polynucleotide strands twisted into a double helix shape, made up of a sugar-phosphate backbone and four nitrogenous bases.

List the four nitrogenous bases found in DNA and their pairing partners.

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

What are the three components of a nucleotide?

A sugar-phosphate backbone, a phosphodiester bond, and a nitrogenous base (A, T, C, or G).

Briefly explain the seven steps of DNA replication including key enzymes.

1. Unzipping (Helicase), 2. Stabilizing (SSB proteins), 3. Priming (Primase adds RNA primers), 4. Building & Extending (DNA Polymerase builds new DNA), 5. Read (Primers removed by exonuclease, replaced with nucleotides), 6. Joining (Ligase joins fragments), 7. Proofreading (DNA Polymerase checks and fixes errors).

What does it mean to say that DNA replication is semi-conservative?

New DNA consists of one strand from the original parent DNA and one newly synthesized strand.

What are the two main steps of protein synthesis?

Transcription (DNA transcribed into mRNA) and Translation (mRNA translated into protein).

Where does transcription occur in a eukaryotic cell?

In the nucleus.

Where does translation occur in both eukaryotic and prokaryotic cells?

In the cytoplasm.

Describe the process of transcription.

Transcription is the process where DNA is transcribed into mRNA.