DNA , Genes, and Chromosomes

B-4.2 Summarize the relationship among DNA, genes, and chromosomes.

Key Concepts

n  Chromosome

n  DNA

n  Gene

What You Already Know… In the 7th grade, you summarized how genetic information is passed from parents to offspring using the terms genes, chromosomes, inherited traits, genotype, phenotype, dominant traits, and recessive traits.

It is Essential For You to Know…

n  DNA, genes and chromosomes compose the molecular basis of heredity.

OBJECTIVES n  Summarize the relationship among DNA,

genes, and chromosomes.

n  Recall the basic structure of chromosomes and genes.

n  Illustrate or interpret an illustration of the relationship of a chromosome, DNA, and genes using words or diagrams.

Vocabulary

1.  Chromosome 2.  DNA 3.  Gene

Genes Genes are located on chromosomes in the cell’s nucleus. Chromosomes are long threads of DNA tightly coiled.

n  Each organism must inherit a single copy of every gene from both its parents.

n  When an organism produces its own gametes those 2 sets of genes must be separated from each other so that each gamete contains just one set of genes.

What Exactly is a Gene? n  A gene is a section of DNA in a

specific region of a specific chromosome.

n  Genes code for specific proteins to be produced, which cause specific characteristics in living things.

n  There are dominant and recessive forms of genes.

n  Each chromosome consists of hundreds of genes determining the many proteins for an individual organism.

Zoom in on a Chromosome