1. Vocabulary Words DNA Nucleus Meiosis Crossing Over Haploid Diploid
Chromosomes
RNA
Protein
Amino Acid
Transcription
Translation
Codon
Genes
Nucleotide
Protein Synthesis
Mutation

2. Overview of Meiosis
Meiosis involves two successive cell divisions with no replication of genetic material between them. This results in a reduction of the chromosome number from diploid to haploid.
Meiosis is a form of cell division that leads to the production of gametes.
Gametes contain half the number of chromosomes of an adult body cell
Gametes are haploid, containing only 1 set of chromosomes.
Adult body cells (somatic cells) are diploid, containing 2 sets of chromosomes.

5. Features of Meiosis
Meiosis includes two rounds of division – meiosis I and meiosis II.
During meiosis I, homologous chromosomes become closely associated with each other during a process called Crossing Over.
Crossing over is a genetic recombination between non-sister chromatids. It is also a physical exchange of regions of the chromatids
These homologues are then separated from each other in anaphase I.

7. Meiosis Cont’d
Meiosis produces haploid cells that are not identical to each other.
Genetic differences in these cells arise from:
-crossing over
- random alignment of homologues in metaphase I (independent assortment)
Mitosis produces 2 cells identical to each other.

8. DNA & Protein Synthesis

9. DNA Deoxyribonucleic Acid A molecule made up of nucleotide base pairs.
These base pairs determine the genetic make-up of an organism

10. DNA Carries information from one generation to the next
Puts that information to work by determining heritable characteristics
Must be easily copied since almost every new cell gets a copy

11. DNA Structure Made up of nucleotides Nucleotides have 3 parts:
Deoxyribose: sugar
Phosphate group
Nitrogenous (nitrogen containing) base
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)

12. How the bases pair in DNA…
A T (A pairs with T)
C G (C pairs with G)

13. DNA and Cell Function
DNA holds the code to help the cell make proteins.
Transcription and Translation help turn the information stored as DNA into a useable protein

14. Quick Review of Proteins
Made of amino acids
There are only 20 amino acids to make up thousands of different proteins
Examples
Keratin
Hemoglobin
Actin
Myosin
Elastin
insulin

15. How are Proteins made? Proteins are made when DNA is copied into RNA.
Then the RNA leaves the nucleus to couple with amino acids
The amino acids connect to make proteins.

16. PROTEIN SYNTHESIS
DNA
Step 1. TRANSCRIPTION
(nucleus)
mRNA
Step 2. TRANSLATION
(ribosome)
tRNA
PROTEIN

17. RNA Like DNA, made of nucleotides Disposable copy of DNA segment
3 differences:
1) sugar= ribose
2) single stranded
3) instead of the base thymine (T), RNA uses uracil (U)

18. Transcription (Step #1)
makes mRNA
Starts in the nucleus
Uses 1 side of DNA as a template
Copies 1 gene at a time

19. Details of the Process
1.RNA polymerase attaches to DNA and it separates the 2 DNA strands (unzips the strand)

20. 2. RNA polymerase synthesizes the mRNA strand using complimentary base- pairing
Once the MRNA strand is finished, it will leave the nucleus and head to a ribosome

21. Remember…there aren’t “T” bases in RNA
“C” binds with “G”
DNA “A” binds with RNA “U”

22. Translation (Step 2)
Occurs in the ribosome.
A group of 3 mRNA bases makes up a “codon” (think of as a “code word”)
each codon specifies a particular amino acid
Each codon will signal
that amino acid to join
the chain!