Unit 1 Compendium 2- Genetics

I. Patterns of Chromosome Inheritance

A. Chromosomes and the Cell Cycle
1. Humans have 46 chromosomes in 23 pairs: 22 control traits, 1 controls sex
2. Cell Cycle- occurs for cell duplication
a. Interphase- Growth 1, Synthesis, Growth 2
b. Mitosis and Cytokinesis

B. Mitosis- Cell duplication division
1. Prophase- the nucleolus dissappears and duplicated chromosomes appear, centrosomes
begin moving apart, and spindle starts to form
2. Metaphase- Centromeres of duplicated chromosomes are aligned at the equator, spindle
fibers attached to sister chromatids come from opposite spindle poles.
3. Anaphase- Sister chromatids part and become daughter chromosomes that move toward
the spindle poles. Each pole recieves the same number and kind of chromosomes as the
parent cell.
4. Telophase- Daughter cells are forming as nuclear envelopes and nucleoli reappear.
Chromosomes will become indistinct chromatin.
5. Cytokinesis- Cytoplasm and oganelles divide and cell division completes.

C. Meiosis- Reduction division- involves two divisions equaling 4 daughter cells with half as many chromosomes as the parent cell.
1. Meiosis 1- duplicated homologous pairs synapse and separate. (Same as Mitosis)
2. Meiosis 2 and Fertilization- sister chromatids separate becoming daughter chromosomes, which mature into Gametes (sex cells).

D. Comparison of Meiosis and Mitosis
1. Mitosis produces diploid cells (46 chromosomes in each)
2. Meiosis produces haploid cells (23 chromosomes in each) or sex cells.
a. Spermatogenesis- production of sperm- each daughter cell, or sperm, have only 23
chromosomes, making them haploid.
1. A male produces 300,000 sperm per minute, or 400,000,000 per day.
b. Oogenesis- production of eggs- each egg is also haploid, and can not complete meiosis 2
without a sperm.

E. Chromosome Inheritance
1. Abnormalities in chromosome inheritance happen because of number and structural
changes in chromosomes.
a. The most common is trisomy 21, or Down Syndrome
b. Chromosomal structure changes most often lead to physical abnormalities.

II. Patterns of Genetic Inheritance

A. Genotype and Phenotype
1. Genotype- genes of an individual for a particular trait or traits; Letters in a punnett
square: AA, Aa, aa.
2. Phenotype- visable expression of a genotype, such as brown eyes or blonde hair.

B. One- and Two- Trait Inheritance
1. Allele- alternate form of a gene that happens in the same spot on chromosomes.
a. Dominant Allele- A
b. Recessive Allele- a
c. Homozygous Dominant- AA
d. Heterozygous- Aa
e. Homozygous Recessive- aa
2. Combining genotypes results in multiple gamete types (WwSs)
3. Just as traits are given from parents to children, certain diseases can be given as well.
(Ex: Sickle-cell, PKU, Tay-Sachs, Huningtons)

C. Beyond Simple Inheritance Patterns
1. Polygenic traits, like height and skin color, are determined by multiple sets of alleles.
2. Traits, like blood type, are determined by multiple alleles where the gene exists in many
forms (Ex: Iªi = blood type A).

D. Sex- Linked Inheritance
1. X- linked- Traits attaxhed to the X chromosome.
a. Ex: Color Blindness, Muscular Dystrophy, Hemophilia.

III. Cancer

A. Cancer Cells
1. Characteristics: Lacks differentiation, have abnormal nuclei, have unlimited replicative
potential, form tumors, have no need for growth factors, and undergo Angiogenesis
(formation of new blood vessels) and Metastasis (form new tumors far from primary
tumor).
2. Types: Carcinomas (epithelial tissue), Sarcomas (muscle and connective tissue),
Leukemia (blood), and Lymphomas (lymphatic tissue).

B. Causes and Prevention of Cancer
1. Causes: Heredity, Carcinogens (chemicals), Radiation, Tobacco, Pollutants (asbestos,
radon), and Viruses ( Hep B and C).
2. Prevention: Watch what you eat, watch for occupational hazards, keep an eye on hormone
therapies, get tested and vaccinated, avoid obesity, alcohol, and radiation. All of these can
possibly trigger a cancer gene and make it spread.

C. Diagnosis of Cancer
1. Seven Warning Signs
a. Change in bowel or bladder habits
A sore that does not heal
Unusual bleeding or discharge
Thickening or lump in breast or elsewhere
Indigestion or difficulty swallowing
Obvious change in wart or mole
Nagging cough or hoarseness
2. Routine Screening Tests
a. ABCD of Melanoma- Asymmetry, Border, Color, Diameter
b. Shower self-exam- breast or testicular
c. Mammogram, CAT scan, or MRI
d. Blood tests- tumor marker or genetic

D. Treatment of Cancer
1. Standard Therapy- Surgery, Radiation, Chemotherapy, Bone marrow transplant.
2. Newer Therapies- Immunotherapy, p53 Gene Therapy

IV. DNA Biology and Technology

A. DNA and RNA
1. DNA- double helix- complimentary paired bases bonded by either 2 or 3 hydrogen bonds.
2. RNA- single strand- no need for hydrogen bond
a. Types of RNA: Ribosomal (rRNA), Messanger (mRNA), and Transfer (tRNA).

B. Gene Expression
1. Protein strand types: amino acid sequence, alpha helix, beta sheet, and tertiary.
2. Transcription- a DNA strand acts as a template for RNA.
3. Translation- the sequence of codons of mRNA specifying the sequence of amino acids in a polypeptide.
a. Genetic Code- a triplet code of amino acids, also known as a codon.

C. Genomics- study of all the nucleotide sequences, including structural genes, regulatory sequences, and non coding DNA segments, in the chromosomes of an organism.
1. Protemics- study of structure, function, and interaction of cellular proteins. 2. Bioinformatics- application of computer technologies to the study of the genome.
3. A person's genome can be modified through gene therapy.
a. Ex Vivo Gene Therapy- used to treat children with Immunodeficiency disorders; Introduces missing ADA into the defective gene, correcting it.
b. In Vivo Gene Therapy- used to treat patients with Cystic Fibrosis; Introduces a missing gene via the respiratory system.

D. DNA Technology
1. Cloning- the production of genetically identical DNA, cells, or organisms asexually.
2. Genetic Engineering- Altering DNA for environmental or industrial purposes.

(All pictures thanks to Google images)