1. Meiosis, DNA Structure & Mutations
Genetics & Heredity
Meiosis, DNA Structure & Mutations

2. Reproduction
Reproduction is the process by which an organism produces others of the same kind.

3. Sexual Reproduction Requires a sperm cell and an egg cell.
Requires two organisms.

4. Fertilization When a sperm joins with an egg, and a zygote forms.
Zygote- The beginning of life that forms into a new organism.

5. New organisms are made from only one parent.
Asexual Reproduction
New organisms are made from only one parent.
The new organism is identical to the parent.

6. Meiosis produces ONLY sperm and egg cells.
(AKA gametes!!)

7. Haploid vs. Diploid
Haploid- Cell that has one of each type of chromosome.
Diploid- Cell whose chromosome occurs in pairs.

8. Sperm
23 Chromosomes
Haploid
Baby
46 Chromosomes
Diploid
Egg
23 Chromosomes
Haploid

9. Sometimes sex cells are made with the wrong number of chromosomes.
Mistakes With Meiosis
Sometimes sex cells are made with the wrong number of chromosomes.
These organisms may not grow normally.

10. DNA: (Deoxyribonucleic Acid)
Chromosomes are made out of DNA.
DNA looks like a double-helix, or a twisted ladder.
DNA codes for the creation of proteins.

11. Structure of DNA DNA is made up of repeating series of nucleotides.
A nucleotide consists of:
Sugar Group
Phosphate Group
Nitrogen Base

12. Four Nitrogen Bases Adenine, Thymine, Guanine, and Cytosine
These bases make up the “steps” in the DNA ladder.

13. Pairing Adenine always binds to Thymine A----T
Guanine always binds to Cytosine G----C

16. DNA Replication
In order for mitosis and meiosis to occur, DNA must replicate!
The DNA strand “unzips” and two new strands of DNA forms.

18. Genes A gene is a section of DNA on a chromosome.
A gene has the instructions for making a specific protein.

19. Mutations a mutation is any change in a gene or a chromosome
When DNA is copied wrong, the proteins made from the DNA will be wrong.
This can lead to a wide range of genetic diseases.

20. Mutations continued… Can cause: a cell to produce an incorrect protein
Could affect the organism’s phenotype
mutations in body cells (somatic) are not passed on to offspring, BUT mutations in the sex cells are

21. Types of Mutations
1. Substitution: a base pair is substituted for another pair.
2. Addition: a base pair is added into the strand
3. Deletion: A base pair is removed from the strand

22. Effects of Mutations: Harmful:
reduces the chance of an organism’s survival and/or reproduction
Helpful:
increases the chance of an organism’s survival and/or reproduction