1. Genetics: Chromosomes, Alleles, Genes, Mutations
Genetics (the study of inheritance): The scientific discipline involved with studying how genes/traits are passed from parent to offspring.

2. Genes and Alleles
Gene: a heritable factor that controls a specific characteristic
Located in specific places on chromosomes
Humans have roughly 20,000-25,000 genes.
Alleles: alternative forms of gene
Example:
Gene: eye color
Alleles: blue vs. brown

3. Chromosomes Prokaryotes: ‘Naked DNA’ Eukaryotic Chromosomes:
Made of DNA and proteins
Two Types:
Autosomes (non sex chromosomes)
Sex Chromosomes
Two parts
Sister Chromatids
Centromere
Homologous Chromosomes: chromosomes that have the same genes as each other, arranged in the same sequence, but not necessarily the same alleles (forms) of those genes

4. Chromosome & Gene Numbers of Different Organisms

5. Karyotyping
A karyotype is a display (micrograph) of the number and type of chromosomes a nucleus contains.
Cells are examined in metaphase of mitosis.
The stained chromosomes are arranged according to size, structure, centromere position, and banding pattern.

6. Human Karyotype (Male or Female?)

7. How are Karyotypes Useful?
One of the main reasons for karyotyping is to find out whether a fetus has Down Syndrome or other chromosomal abnormalities.
Karyotyping can be done by extracting and examining fetal cells (amniocentesis) or through chorionic villus sampling (examining cells from the placenta).

8. What are ‘genes’? (Click Here for a Helpful Animation)
Genes are segments of DNA molecules (specific sequences of A, T, G & C) that code or carry the instructions for making a protein. Humans have approximately 20,000 different genes across 46 chromosomes.

9. Chromosome 21

10. Sample Gene Sequence

11. Transcription & translation
Protein synthesis

12. Protein Synthesis
Protein synthesis is the process by which DNA in the nucleus of a cell directs the production of protein(s).
Proteins determine virtually everything about you.
Proteins are polymers (polypeptides) made up of long chains of amino acids (monomers). They have very complex 3 dimensional shapes.
The specific shape of a protein will determine its function in the body. Proteins can be structural (make up muscle), function as enzymes, participate in the immune system, etc.).
The production or lack of production of a particular protein can have dramatic effects on the body

13. There are 2 major stages to protein synthesis
The classic view of the Central Dogma of biology states that the basic mechanism of reading and expressing genes is from DNA to RNA to Protein. This chain of events occurs in all living things—from bacteria to humans.
DNA CODES FOR RNA, WHICH GUIDES THE SYNTHESIS OF PROTEINS

14. A Summary of RNA Types we’ll be working with
FUNCTION
mRNA
Messenger RNA is a complimentary copy of a DNA gene and is enough genetic information to code for a single polypeptide.
tRNA
Transfer RNA will transfer 1 of 20 amino acids to the ribosome for polypeptide formation.
rRNA
Ribosomes are composed of ribosomal RNA and protein.

15. A Brief Overview of protein synthesis

16. The Genetic Code is Written in Triplets (Codons)
When a triplet is found in an mRNA molecule, it is called a codon or codon triplet. Each code corresponds to 1 of 20 amino acids.

17. *PRACTICE TRANSCRIBING AND TRANSLATING A GENE*
Helpful Animations
Protein Synthesis Step-by-Step Animation
Transcription and Translation (Stolaf)
Transcription Detail and Translation Detail (UofNeb)
Transcription and Translation (McGraw Hill)
mRNA Splicing (McGraw Hill)
Crash Course Biology (Transcription & Translation)
*PRACTICE TRANSCRIBING AND TRANSLATING A GENE*

18. The one gene--one polypeptide hypothesis
Scientists used to believe that one gene coded for only one protein (polypeptide). This, however, isn’t entirely accurate. Why?
mRNA transcribed from one gene may be spliced in different ways to form different proteins.
RNA molecules produced from one gene may themselves be functional.

19. Eukaryotic Gene Regulation (Transcription Factors)
Eukaryotic cells MUST control what genes are expressed at different times in the organism’s lifetime.

20. Mutations
Mutations are heritable changes in the sequence of bases in a gene.
Changes in the sequence of bases can cause changes to the amino acid sequence, altering the structure and function of the protein to be made.

22. DNA Mutations (Explore Further)
Point Mutations:
Caused by base pair substitutions
The replacement of one nucleotide and its partner with another pair
May cause a change to the protein being made (missense/nonsense mutation) or not (silent mutation).
Missense  amino acid change
Nonsense early stop codon
Frameshift Mutations:
Caused by inserting or deleting a nucleotide pair
Changes the amino acid sequence from the point of the mutation to the end of the polypeptide chain.
A shift in the DNA changes how the codons are read and potentially a big change to the protein being made.
Causes of DNA mutations include random cell errors and chemical,
radiation and/or UV exposure. Mutations are heritable if the mutation is carried in the gametes (sex cells – sperm or egg)
Link: TYPES OF DNA MUTATIONS

23. DNA MUTATIONS

24. Chromosomal Mutations (Explore Further)
Deletion
Removes a chromosomal segment
Duplication
Repeats a segment
Inversion
Reverses a segment within a chromosome
Translocation
Moves a segment from one chromosome to another nonhomologous one
Alteration of Chromosome number
Nondisjunction (we will discuss this more during Meiosis)

25. Sickle-Cell Anemia (Symptoms can be relatively mild to severe)
Signs & Symptoms:
Anemia
Shortness of breath, dizziness, headaches, coldness in hands/feet, pale skin, jaundice.
Pain Throughout the Body
Blocked Blood Flow
Infections
Pulmonary Hypertension
Stroke
Multiple Organ Failure
*Sickle-Cell Disease Offers Protection Against Another Disease Called Malaria*

26. SICKLE-CELL ANEMIA
Hemoglobin, found in RBC’s, carries oxygen throughout the bloodstream.
All cells require oxygen for cellular resp.
Sickle-Cell Anemia results from a single point mutation that alters the shape of the hemoglobin molecule, resulting in sickle-shaped red blood cells.

27. The Most Unusual Mutations
Sickle Cell Anemia
The Most Unusual Mutations
ADDITIONAL VIDEOS

28. Detecting Fetal Abnormalities
Amniocentesis
Chorionic Villus Sampling

29. The Human Genome Project
Genome: the whole of the genetic information
of an organism
The Human Genome Project
Completed in 2003
The mapping of human chromosomes/genes.

30. The Human Genome Project