1. Heredity

2. Mendelian Genetics

3. Introduction to Genetics
GENETICS – branch of biology that deals with heredity and variation of organisms.
Chromosomes carry the hereditary information (genes)
Genes  DNA  RNA  Proteins

4. Chromosomes (and genes) occur in pairs
Homologous Chromosomes (1 from mommy and 1 from daddy)
Unique combinations of genes occur in sexual reproduction

5. Terminology you need to know:
Gene – a unit of heredity;
a section of DNA sequence
encoding a single protein.
Alleles – two genes that occupy the same position on homologous chromosomes and that cover the same trait (like ‘flavors’ of a trait).

6. Homozygous – having identical genes (one from each parent) for a particular characteristic.
Heterozygous – having two different genes for a particular characteristic
Blue is from father
Red is from mother
HomozygousAA aa
Heterozygous Aa

7. Dominant – the allele of a gene that masks or suppresses the expression of an alternate allele
Recessive – an allele that is masked by a dominant allele

8. Phenotype – the physical appearance
of an organism.
Genotype – the genetic makeup of an organisms

9. Monohybrid cross Parents differ by a single trait.
Crossing two pea plants that differ in stem size, one tall one short
T = allele for Tall
t = allele for dwarf
TT = homozygous tall plant
t t = homozygous dwarf plant
T T  t t

10. Punnett square A useful tool to do genetic crosses
For a monohybrid cross, you need a square divided by four….
Looks like
a window
pane…
We use the
Punnett square
to predict the
genotypes and phenotypes of
the offspring.

11. Using a Punnett Square TT and t t T T  t t
STEPS: 1. determine the genotypes of the parent organisms 2. write down your "cross" (mating) 3. draw a p-square Parent genotypes:
TT and t t
Cross
T T  t t

12. Punnett square
4. "split" the letters of the genotype for each parent & put them "outside" the p-square
5. determine the possible genotypes of the offspring by filling in the p-square
6. summarize results (genotypes & phenotypes of offspring)
T T
T t
Genotypes:
100% T t t
Phenotypes:
100% Tall plants

13. DNA

14. What is DNA?
1. Organic molecule
2. Nucleic acid

15. Where is it located?
1. Nucleus
2. Chromosomes X
DNA

16. Structure of DNA Nucleotides a. Phosphoric Acid b. Deoxyribose sugar
c. Nitrogenous bases:
Adenine-Thymine
Guanine-Cytosine
2. Ladder Shape
3. Double strand, helix twist

17. Transcription: mRNA is copied off of DNA In nucleus Steps:
DNA untwists
DNA unzips
RNA codons line up

18. Transcription: mRNA DNA Code A T C G U A G C I I I mRNA has:
Ribose sugar
Uracil instead of thymine bases
Nuclear membrane allows it to leave!
mRNA A T C G U A G C I I I
DNA Code

19. Translation Conversion of the message (mRNA Code) Into a protein
By the ribosome factories

20. Replication to Proteins

21. Mitosis

22. Mitosis Is the division of the cell’s nucleus.
Cells under go mitosis for a number of reasons including:
Growth and repair
Increased efficiency (Surface to volume ratio)
Better communications with the cell
Mitosis is apart of the cell’s life cycle

23. M - Mitosis G1 - Growth, normal activities. M G2 S – DNA replication
G2 – Preps for mitosis
M - Mitosis S

24. Phases of Mitosis
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis

25. Mutation

26. Mutation Any change that occurs in the DNA sequence
Can be caused by errors in replication, transcription, cell division, or by external factors.
Mutations can be beneficial or harmful

27. Locations of Mutations
Reproductive cell - The altered gene becomes part of the offspring.
Body (somatic) cell – Altered gene results in changes in a single cell. May result in cancer. Will not be passed to offspring.

28. Types of Mutations

29. Point Mutation

30. Translocation

31. Deletion