1. Chromosomes, Genes, and Mutations

2. What are chromosomes?
Chromosomes are packages of tightly-coiled (condensed) DNA
Each chromosome is tightly coiled around proteins called histones

3. What are chromosomes?
Each human has 23 sets (pairs) of chromosomes, or 46 total chromosomes

4. What are genes? A molecular unit of heredity
The name for sections of DNA (and therefore RNA) that code for a specific protein (which has a specific function in the organism)

5. What are genes?
Since genes are bands/sections of DNA, that means genes are also bands/sections of chromosomes

6. How are genes inherited?
Each person has two copies of each gene – one on each chromosome
You inherit one chromosome from your mom, and one chromosome from your dad
More on meiosis later…

7. How are genes mutated?
Genes can be mutated when the DNA is mutated or when the chromosomes are mutated
There are two types of DNA (gene) mutations:
Point Mutations: a change in a single base pair
Frameshift Mutations: a single base is added or deleted from DNA
Chromosomes can be mutated as well (long segments of DNA)…

8. What are examples of chromosomal mutations?
Deletions: part of the chromosome is left out

9. What are examples of chromosomal mutations?
Inversions: part breaks out and reinserts itself backwards

10. What are examples of chromosomal mutations?
Translocations: part breaks off and is added into a different chromosome

11. What are examples of chromosomal mutations?
Non-Disjunction: failure of homologous chromosomes to separate properly during meiosis

12. What causes chromosomal mutations?
Problems that occur during meiosis

13. What causes chromosomal mutations?
Environmental agents (x-rays, UV light, radioactivity)

14. What are the results of chromosomal mutations?
If it occurs in gametes (sex) cells:
Can cause birth defects, miscarriage, or no change
Few are passed on to next generation because zygote usually dies
If it occurs in somatic (body) cells:
Can lead to cancer
Can have no change