Biology: DNA, Genes & Chromosomes Lecture Review

These flashcards cover key concepts and facts regarding DNA, genes, and chromosomes as discussed in the biology lecture.

What are the two types of organisms based on cell structure?

Unicellular organisms (e.g., bacteria) and multicellular organisms (e.g., plants and animals).

What is the difference between eukaryotic and prokaryotic cells?

Eukaryotic cells (plants and animals) contain a nucleus; prokaryotic cells (bacteria) do not.

What is DNA?

Deoxyribonucleic acid, a polymer of nucleotides that carries genetic instructions for the development and functioning of living organisms.

What are the components of a nucleotide?

Phosphate, sugar, and a nitrogen-containing base.

What type of molecule is DNA?

A polymer made of repeating units called nucleotides.

How many types of nitrogen-containing bases are in DNA, and what are they?

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

What is complementary base pairing?

The pairing of nitrogen-based nucleotides in DNA; A pairs with T, and C pairs with G.

What is the structure of DNA?

A double helix formed by two strands of nucleotides twisted around each other.

What is a gene?

A short length of DNA that codes for a specific characteristic.

How many genes do humans have?

Approximately 20,000 genes.

What is the purpose of DNA?

To store the information needed to build proteins and determine the characteristics of an organism.

Who discovered the structure of DNA?

James Watson and Francis Crick, with significant contributions from Rosalind Franklin.

What is a chromosome?

A tightly coiled structure made of DNA and proteins that carries genetic information.

How many pairs of chromosomes do humans have?

23 pairs.

What is genetic inheritance?

The process through which genes are passed from parents to offspring.

What are dominant and recessive genes?

Dominant genes are expressed in the phenotype even when only one copy is present; recessive genes are only expressed when two copies are present.

How can DNA be extracted from cells?

By using a mixture that breaks down cell membranes and separates the DNA, typically using detergents and cold alcohol.

What is the significance of Rosalind Franklin's work?

Her x-ray crystallography images helped in discovering the helical structure of DNA.

What is the role of DNA in living organisms?

It contains the genetic blueprint that guides all cellular processes including protein synthesis.

How does DNA compare in length to the solar system?

The total length of DNA in all cells of a human body could stretch to twice the distance of the solar system.