Science 9 - Inheritance: Chromosomes and Genetic Inheritance

Flashcards covering key concepts from the notes on chromosomes and genetic inheritance.

What is heredity?

The passing of traits from parent to offspring.

What is variation?

Differences among individuals.

What is genetics?

The study of heredity and variation.

What carries genes on a chromosome, and how is it structured?

Chromosomes are tightly packed in the nucleus; they carry genes; DNA is coiled around histone proteins.

Where are chromosomes located in prokaryotes?

In the nucleoid region of the cytoplasm.

Where are chromosomes located in eukaryotes?

In the nucleus.

What are homologous chromosomes?

Pairs of chromosomes that are similar in size and gene content; one from each parent.

What is the diploid number (2n)?

The number of chromosomes present in body (somatic) cells.

How many chromosomes do humans have, and how are they arranged?

46 chromosomes arranged in 23 pairs.

What does homologous mean?

Origin or function are the same; homologous refers to matching chromosome pairs with similar genes.

What are gametes and how many chromosomes do they have?

Egg and sperm cells; contain the haploid number (n) of chromosomes.

What are sex chromosomes in humans and how do they differ in males and females?

Sex chromosomes (genosomes); females typically XX, males XY.

What is mitosis?

Cell division for somatic (body) cells.

What is meiosis?

Cell division that produces sex cells (gametes).

What is Interphase in the cell cycle?

Stage of growth, DNA replication, and cell functions; DNA is replicated.

What is the nucleus?

An organelle that contains DNA and holds genetic information.

What is the ranking from largest to smallest?

Organism > Cell > Nucleus > Chromosome > Gene > DNA.

What happens to DNA during Interphase?

DNA is duplicated before mitosis.

What is genetic inheritance?

The passing of traits from generation to generation.

What do the letters J and j in the notes illustrate?

Dominant and recessive alleles (J is dominant, j is recessive).

What is a dominant trait?

Expressed when at least one dominant allele is present; it overrules recessive.

What is a recessive trait?

Expressed only when both alleles are recessive (both copies present).

What is genotype?

The genetic makeup or allelic combination of an organism.

What is phenotype?

The observable traits or characteristics of an organism.

What are the four main types of genetic inheritance?

Dominant, Recessive, Codominance, and Incomplete Dominance.

Who is Gregor Mendel?

Gregor Johann Mendel, Father of Genetics; studied garden peas.

What is the F1 generation?

First Filial Generation; offspring of purebred P1 plants.

What is the F2 generation?

Second Filial Generation; offspring of the F1 generation.

What is codominance?

Both alleles are expressed in the phenotype (e.g., AB blood type).

What is incomplete dominance?

A blending phenotype in the heterozygote (e.g., red and white produce pink).

What is the genotype ratio for a cross of Rr x Rr?

1 RR : 2 Rr : 1 rr.

What is the phenotype ratio for the Rr x Rr cross in incomplete dominance?

Red : Pink : White = 1 : 2 : 1.

What is a gene?

A factor that controls the appearance (hereditary unit).

What is an allele?

An alternative form of a gene.

What is a chromosome?

A structure made of DNA and proteins that carries genes.

What is haploid number (n)?

The chromosome number in gametes.

What are somatic cells vs sex cells?

Somatic cells: all body cells; Sex cells: sperm and egg.