Chapter 19 -21 Rev.

Chapter 19

Cancer

1. Cancer Cells

Although cancer is actually over 100 different diseases and each type of cancer can vary from another, these characteristics are common to cancer cells. Cancer cells lack differenation and do not contribute to function. They do not undergo apoptosis, they enter the cell cycle an unlimited number of times. They form tumors and do not need growth factors to signal them to divide. They gradually become adnormal-carcinogensis is comprised of initiation, pr0motion and progression. They undergo angiogenesis and can spread throughout the body. Cells become increasingly abnormal due to mutations in proto-oncogenes and tumor suppressor genes. Proto-oncogenes, they promote cell cycle activity and restrain apoptosis.

2.Causes ans Prevention of Cancer

A mutagen is an agent that causes mutations. A carcinogen is a chemical that causes cancer, for ex: by being mutagenic. Tobacco smoke conatins a number of organic chemicals that are known mutagens including nitrosonor-nicotine and benzo.

3. Diagnosis of Cancer

At present, daignosis of cancer before metastasis is difficult. Pap test for cervical Cancer, mamogram for breast cancer, tumor mark tests-blood tests that detect tumor antigens/anitbodies. Tests for genetic mutations of oncogens and tumor suppressor genes. A biopsy and imaging is used to confirm the diagnosis of cancer.

4. Treatment of Cancer

There are several methods of treatment for cancer, the common ones are surgery, rediation, and chemotheraopy. The other methods are bone marrow transplants, immunotherapy. Other therapies on top of these ones such as inhibitory drugs for angiogenesis and metastasis, which are being investigated.

CHAPTER 20

Patterns of Genetic Inheritance

1. Genotype and Phenotype

Genotype refers to the genes of one individual. Alternative forms of a gene having the same position on a pair of chromosomes and affecting the same trait are called alleled. It is customary to desginate an allele by a letter which represents the specific trait it contorls a dominate allele and is assigned an uppercase letter, while a recessive allel is given the same letter but in lowercase.

2. One and Two Trait Inheritance

The first step in doing one trait problems is to determine the genotype and then the gametes. An individual has 2 allelesfor every trait, but a gamete has one allele for every trait. TThe next step is to combine all possible sperm with all possible eggs. If there is more than one possible sperm and or egg, a Punnett Square is helpful in determining the genotypic and phenotypic ratio among the offspring.

3. Beyond Simple Inhheritance Patterns

In some patterns of inheritance, the alleles are not just dominate or recessive. Plygenic traits, such as skin colo and height are controlled by more then one set of allels. The dominate alleles has an additive effect on the phenotype. In incomplete dominance the heterzygote is intermidiate between two homozygous. In codominance, both dominate alleles are expressed equally. Multiple Allele Inheritance patter is exemplified in humans by blood type inhertiance.

4. Sex-Linked Inheritance

Many genes on the x chromosomes, such as those that dtermine normal vision as opposed to color blidness, are unrelated to the gender of the individual. A pedigree for an X linked recessive disorder shows that the trait often passes from grandfather to gradson by was of carrier daughter. Like most x-linked disorders, color blindess, muscular dystrophy, and hemophilia are recessive.

CHAPTER 21

DNA BIOLOGY & TECHNOLOGY

1. DNA & RNA Structure and Function

DNA is the genetic material found in the chromosomes. It replicate, stores info and mutates for gentice varibility. The structure of DNA is a double helix composed of 2 polyhucleotide strands. Each nucleotide is composed of a deoxyribose sugar, a phosphate, and a nitrogen containing base. The base A is bonded to T, and G is Bonded to C. The replication of DNA is the strands unzip and a new complementary strand forms opposite each old strand, resulting in tow identical DNA molecules. The structure of RNA, is a single starnded nuclei acid in which the base U occurs instead of T. The 3 forms of RNA are: rRNA, mRNA, tRNA.

2. Gene Expession

Gene expression leads to the formation of a product, usually a protein. Proteins differ by the sequence of their amino acids. Transcription- Occurs in the nucleus. The DNA triplet code is passed to an mRNA that contains codons,. Intorns are removed from mRNA during mRNA processing. Translation: Occurs in the cytoplams at the ribsomes tRNA molecules bind to their amino acids and then their anticodons pair with mRNA codons.