Compendium Review # 2

TABLE OF CONTENTS

PATTERNS OF CHROMOSOME INHERITANCE

1. Chromosomes and the Cell Cycle
a. Karyotype
b. cell cycle
2. Mitosis
a. phases
b. Cytokinesis
c. Importance of
3. Meiosis
a. Stages
b. Significance of
4. Comparison of Meiosis and Mitosis
a. Process
b. Spermatogenesis and oogenesis
5. Chromosome Inheritance
a. Changes in chromosome #
b. Changes in Chromosome Structure

DNA BIOLOGY AND TECHNOLOGY

6. DNA and RNA Structure and Function
a. Structure and Replication of DNA
b. Structure and function of RNA
7. Gene Expression
a. Structure and function of Proteins
b. Expression
c. Transcription
d. Translation
e. Review
f. Regulation

8. Genomics

a. Sequenced

b. Function and Comparative Genomics
c. Proteomics and Bioinformats are new endeavors

d. Can be modified

9. DNA Technology

a. Genes can be isolated and cloned

b. Specific DNA Sequences can be cloned

c. Biotechnology Products

CANCER

10. Cancer cells

a. characteristics

b. genetic disease
c. types

11. Causes and Prevention of Cancer

a. Heredity

b. Environmental Carcinogens
c. Dietary choices

12. Diagnosis of Cancer

a. 7 warning signs
b. Routine tests

c. Genetic tests
13. Treatment of Cancer

a. Standard Therapies

b. Newer therapies

PATTERNS OF GENETIC INHERITANCE

14. Genotype and phenotype

a. what they are

15. One-and-two trait inheritance

a. Gametes

b. One trait crosses

c. Two trait crosses
d. Family pedigrees

e. Genetic disorders of interest

16. Beyond Simple inheritance Patterns

a. Polygenic

b. Incomplete dominance and co-dominance

c. Multiple alleles

17. Sex-linked Inheritance

a. X-linked alleles

b. Pedigree for X linked disorders

c. Conclusion

PATTERNS OF CHROMOSOME INHERITANCE

Chromosomes and the Cell Cycle

A karyotype is a visual display of a person's chromosomes. Normal karyotype shows 22 pairs of autosomes and 1 pair of sex chromosomes. Normal sex chromosomes in a female are XX and in a male XY.

The cell cycle is an orderly process that has two parts: interphase and cell division. Interphase is the part most of the cell is spent in. It's the time that organelles carry on their usual functions. There are 3 stages: 1. G1- cell doubles its organelles. 2. S-stage a copy is made of all DNA in the cell. 3. G2 stage cell synthesizes proteins.
Cell division has 2 stages: M(miotic), and cytokinesis.

Mitosis

Mitosis is duplication division that assures that all body cells have the diploid number and the same kinds of chromosomes as the cell that divides. There are 4 stages of Mitosis. 1. Prophase- chromosomes attach to spindle fibers 2. Metaphase - chromosomes align at the equator 3. Anaphase - chromatids separate, becoming chromosomes that move toward the poles 4. Telophase - Nuclear envelopes form around chromosomes and cytokinesis begins.

This cycle is important to our well being. Mitosis, and the proper working, is critical to growth and tissue repair. See illustration at left.*

Meiosis

Meiosis has two cell divisions: meiosis 1 and meiosis 2. First division homologous chromosomes, ones that look alike pair and separate. Second division sister chromatids separate, resulting in four cells with the haploid number of chromosomes that move into daughter nuclei. See illustration at left.*

Comparison of Meiosis and Mitosis

In prophase I, homologous chromosomes pair, there is no pairing in mitosis. In metaphase I, homologous duplicated chromosomes align at equator. In anaphase I, homologous chromosomes separate.

Spermatogenesis and oogenesis is part of Meiosis. Spermatogenesis is the production of sperm males. Oogenesis is the production of eggs.

Chromosome Inheritance

Meiosis is part of gametogenesis and contributes to genetic diversity.
Changes in Chromosome number is when nondisjunction changes the chromosome #'s becoming trisomy and down syndrome.
Changes in sex chromosome numbers can result in gametes that have too few or too many X or Y chromosomes. These could lead to Turner has one sex chromosome X, Klinefelter has XXY, polly-X has more that two X chromosomes, and Jacobs has XYY.

Changes in structure can produce chromosomes that have deleted, duplicated, inverted, or translocated segments. Translocation can cause some cancers and Alagille. Williams disease caused by and cri du chat because of deletion. See illustration at left.*

DNA BIOLOGY AND TECHNOLOGY

DNA and RNA Structure and Function

DNA is a double helix, 2 strands that twist around each other. The strands are polynucleotide strands. Composed of deoxyribose sugar, a phosphate, and a nitrogen- containing base. See illustration on left.*

DNA strands come apart and a new strand forms opposite each old strand. See illustration on left.*

RNA is a single nucleic acid in which the base, uracil occurs instead of thymine. There are 3 forms of RNA: 1. rRNA - found in ribosomes

2. mRNA - carries DNA messages to ribosomes 3. tRNA - tranfers amino acids to the ribosomes where protein synthesis occurs. See illustration to the left.*

Gene Expression

Gene expression leads to the formation of a product, usually protein. Gene expression requires transcription and translation. Transcription is the first step in gene expression. This step occurs in the nucleus. The DNA triplet code is passed to an mRNA that contains dodons. Introns are remved from mRNA during mRNA processing. Translation is the second step and occurs in the cytoplasm at the ribosomes. tRNA molecules bind to their amino acids, and then their anticodons pair with mRNA codons. The illustration to the left show different codons.*

Regulation of gene expression happens at 4 levels: 1. Transcriptional control - degree to which a gene is transcribed. 2. Posttranscriptional control - involves mRNA processing and how fast it leaves the nucleus. 3. Tranlational control - in cytoplasm, affects when translation begins and how long it goes on. 4. Posttranslational control - also in cytoplasm, occurs after protein synthesis.

Genomics

Genomics is the study of all necleotinde sequences, including structural gens, regulatory sequences, and noncoding DNA segments, in the chromosomes of an organism.

Proteomics is the stydy of the structure, function and interaction of cellular proteins.

Bioinformatics is the application of computer technologies to the study of the genome.

A Person's genome can be modified in one of two ways. 1. Ex vivo gen therapy, which is outside the body. 2. In vivo gene therapy which is inside the body.

DNA Technology

Genes can be isolated and cloned. In the illustration below it shows the steps that are taken to clone genes and that bacteria produce a product through same process.*

Specific DNA sequences can also be cloned. Polymerase chain reaction (PCR) is a technique that uses the enzyme DNA polymerase to produce millions of copies of a particular piece of DNA. This would also go into DNA fingerprinting. See illustration to the left.*

Biotechnology products that are genetically engineered bacteria, plants, and animals. Organisms that have had a foreign gene inserted into them are called trangeici organisms. The table below gives examples of them.*

Transgenic bacteria can promote plant health, remove sulfur from coal, clean up toxic waste and oil spills, extract minerals, and produce chemicals. transgenic crops can resist herbicides and pest. Transgenic animals can be given growth hormone to produce larger animals, can supply transplant organs and can produce pharmaceuticals.

CANCER

Cancer Cells

There are 7 characteristics of cancer cells: 1. Cancer cells lack differentiation - looks distinctly abnormal 2. Cancer cells have abnormal nuclei 3. Cancer cells have unlimited replicative potential 4. Cancer cells form tumors 5. Cancer Cells have no need for growth facotrs 6. cancer cells gradually become abnormal 7. Cancer cells undergo angiogenesis and metastasis.

Cancer is a multistage process that is broken down into 3 phases: 1. Initiation 2. Promotion 3. Progression. These stages are illustrated here.*

In this illustration it show the difference between normal and cancer cells.*





There are 4 main types of cancer: 1. Carcinomas - originate in the epithelial tissue. 2. Sarcoma - originate in muscle and connective tissues 3. Leukemias - originate in the blood

4. Lymphoma - originate in lymphatic tissue.

Causes of cancer could be hereditary, caused by environmental carcinogens, and dietary choices.

Diagnosis of Cancer

There are tests that can bring diagnosis of cancer: 1. pap test for cervical cancer 2. mammogram for breast cancer 3. tumor marker tests 4. biopsy and imaging 5. tests for genetic mutations.

There are 7 warning signs of cancer: 1. Change in bowel or bladder habits. 2. A sore that does not heal 3. Unusual bleeding or discharge. 4. Thickening or lump in breast or elsewhere. 5. Indigestion or difficulty in swallowing. 6. Obvious change in wart or mole 7. Nagging cough or hoarseness. Take each letter at the beginning of each sign and it spells out the word CAUTION!

Treatment of cancer can range from radiation and chemotherapy, bone marrow transplants, immunotherapy, gene therapy, inhibitory drugs, which are being investigated.

PATTERNS OF GENETIC INHERITANCE

Genotype and Phenotype

Genotype refers to the alleles of the individual. Phenotype refers to the physical characteristics associated with these alleles. Homozygous dominant individuals (EE) have dominant phenotype. Homozygous recessive individuals (ee) have recessive phenotype. Heterozygous individuals (Ee) have dominant phenotype.

One and two trait inheritance

An individual has two alleles for every trait, a gamete has one allele for every trait.

This punnett square shows how the gametes will turn out.* For a monohybrid x monohybrid a 3:1 ration is expected from offspring. With a monohybrid and recessive cross a 1:1 ratio is expected among offspring.

If an individual is heterozygous for two trait, 4 gamete types are possible as can be substantiated by knowledge of meiosis.

A pedigree shows the pattern of inheritance for a trait from generation to generation of a family.

It was much easier seeing these illustrations above to understand the Autosomal Recessive and Autosomal Dominant disorders, they explain it better than I.

The genetic disorders of interest are: Tay-Sachs, cystic fibrosis, phenylketonuria and sickle-cell diseases, these are autosomal recessive disorders.

Marfan syndrome and Huntington disease are autosomal dominant disorders.

Polygenic traits are skin color and height which are governed by several sets of alleles.

In Incomplete dominance the heterozygote is intermediate between the two homozygotes. In codominance both dominant alleles are expressed equally.

Multiple Allele Inheritance the pattern in exemplified in humans by blood type inheritance.

Sex-Linked Inheritance

Many genes on the X chromosome are unrelated to the gender of the individual. Males usually have the XY chromosomes and females the XX chromosome.


For the Pedigree X linked disorders this illustration* helped me to understand best. Even more so than just reading the text. Like most X- linked disorder, color blindness, muscular dystropy, and hemophilia are recessive.

In conclusion, all of these chapters were packed with great information. I now understand how cancer is formed and what it does to your cells and how the progression can move rapidly. Understanding the small pieces of DNA and how it is replicated is an awesome process. The scientists and people who study this are amazing that they have found so much information to help a world full of people in the future. I can relate to the genes and inheritance. It is interesting how you can put two things together and wonder what it will come out like. I can put that into my own life with seeing what traits my kids got from both of us as their parents. Of course not all went they way we wanted but that is what makes them unique. Although, each of our kids got some of the same characteristics, it is neat to see which of the characteristics they don't share.

*All photos were used from this website.
http://highered.mcgraw-hill.com/classware/selfstudy.do?isbn=0072986867