genetics week 1 part 1: DNA, Chromosomes, and Sex-Determination

Nucleus

The library or the book containing all instructions in a cell.

Chromosome

One chapter in the book containing all genetic instructions.

Genes

Individual words or letters within a chromosome that code for traits.

Homologous Chromosomes

A pair of chromosomes that contain the same genes in the same order.

Macromolecule

A very long molecule, specifically DNA and RNA in the context of nucleic acids.

Nucleotide

The basic building block of DNA and RNA, comprising a pentose sugar, phosphate group, and nitrogenous base.

Purines

Nitrogenous bases with a double-ring structure: adenine (A) and guanine (G).

Pyrimidines

Nitrogenous bases with a single-ring structure: cytosine (C), thymine (T), and uracil (U).

Antiparallel Strands

The orientation where the two strands of a DNA molecule run in opposite directions.

Covalent Bonding

The type of bonding forming the backbone of DNA, linking nucleotide components.

Hydrogen Bonding

Weak interactions holding complementary strands of DNA together.

Denaturation

The process of separating double-stranded DNA into single strands by applying heat.

Renaturation

The reformation of double-stranded DNA from single-stranded DNA.

Chromatin

The combination of DNA and associated proteins within a chromosome.

Histones

Positively charged proteins that help neutralize the negative charge of DNA.

Gametes

The reproductive cells produced by males (sperm) and females (egg).

Dioecious

Species where individuals are either male or female, with separate reproductive structures.

Monoecious

Species that possess both male and female reproductive structures.

XX-XY System

A sex determination system where females have XX chromosomes and males have XY.

ZZ-ZW System

A sex determination system where females have ZW chromosomes and males have ZZ.

What is the function of the nucleus in a cell?

The nucleus acts as the library or the book containing all genetic instructions.

What are homologous chromosomes?

A pair of chromosomes that contain the same genes in the same order, although they may have different alleles.

What are the three components of a nucleotide?

Pentose sugar (Deoxyribose in DNA, Ribose in RNA), Phosphate group, Nitrogenous base.

What is Chargaff's Rule for base pairing in DNA?

The ratio of adenine (A) to thymine (T) is always 1 (A=T), and the ratio of guanine (G) to cytosine (C) is always 1 (G=C).

What is the orientation of DNA strands?

DNA strands are antiparallel, running in opposite directions (5' to 3' and 3' to 5').

How many hydrogen bonds hold A-T and G-C base pairs together?

A-T base pairs are held by two hydrogen bonds; G-C base pairs are held by three hydrogen bonds.

What defines the melting temperature of DNA?

The melting temperature is the specific temperature at which double-stranded DNA (dsDNA) denatures into single-stranded DNA (ssDNA).

What is a nucleosome?

A nucleosome is the basic unit of DNA packaging, consisting of a segment of DNA wound around a core of histone proteins.

Define dioecious and monoecious species.

Dioecious species have individuals that are either male or female, while monoecious species possess both male and female reproductive structures.

What are the sex chromosomes for females and males in the XX-XY system?

Females