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Final
Various Topics in Biology
35
Biology
Undergraduate 1
12/04/2007

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Term
Before cells are able to reproduce,....
Definition
there must be a division of the nucleus and its DNA,
Term
Meiosis
Definition
occurs in germ cells that divide to form gametes (sex cells);

the process by which one diploid eukaryotic cell divides to generate four haploid cells (gametes);
Term
Why is meiosis important?
Definition
Meiosis is essential for sexual reproduction and therefore occurs in all eukaryotes that reproduce sexually;
Term
Binary Fission
Definition
the form of asexual reproduction in single-celled organisms by which one cell divides into two cells of the same size and is used by most prokaryotes.

Results in the reproduction of a living cell by division into two equal or near-equal parts.

i.e. bacterial DNA
Term
organisms that reproduce by binary fission,...
Definition
generally have exponential growth phases;

i.e. bacteria, archaea
Term
Cancer
Definition
a disease caused by the unplanned division and growth of cells;
Term
Cancer is harmful to:
Definition
somatic cells if it occurs early in developement;

cancer in sex cells pass the cancer on to the offspring (germ line)
Term
Cancer phases
Definition
1. Mutation - genetic information (dna) is changed; this causes the cell to divide.

2. Division - cells begin to reproduce rapidly, producing a tumor (abnormal mass of constantly dividing cells)

3. Invasion - Matatasis (spreading of cancer cells throughout the body) occurs;
Term
Carcinogens
Definition
chemicals or radiation that causes mutations;
Term
Proto-oncogene
Definition
normal dna that controls cellular division;

one of the genes that affects cancer;
Term
Proto-oncogene's Function
Definition
1. controls production of growth protein (proteins that cause cells to divide)

2. production of receptor proteins (recieve signals from outside the cell)

3. production of transcription proteins (control gene expression by binding to the DNA)
Term
oncogene
Definition
mutated proto-oncogene; one mutation will result in cancer;
Term
tumor suppressor gene
Definition
gene that controls/stops rapidly dividing cells

i.e. p53 protein/gene
Term
cancer treatments
Definition
1. surgery - removal of tumors

2. radiation therapy - radiation is used to destroy rapidly dividing tumors.

3. Chemo therapy - mixture of anti-cancer drugs to destroy tumors.

(both radiation and chemo therapy are harmful to normal cells)
Term
genotype
Definition
genetic makeup of an individual; (one cant see)
Term
phenotype
Definition
physical characteristics of an individual; (you can see)
Term
autosome
Definition
non-sex characteristics;
Term
sex chromosomes
Definition
determine the sex of an individual;
Term
Mendel's 5 part hypothesis
Definition
1. every gene will have two alleles; (alternate forms or variations of a gene)

2. Law of Segregation - alleles seperate during meiosis.

3. Law of Independent Assortment - allele seperation is random;

4. Dominant allele - mask/hide the expression of another allele; recessive allele - masked/hidden in the presence of another allele;

5. Homozygous - same alleles for a gene (2 dominent or 2 recessive); hederozygous - different alleles for a gene;
Term
Variations to Mendel's Hypothesis
Definition
1. Multiple alleles - gene will have many alleles because of mutations.

2. Co-dominance - two dominant alleles expressed equally (ex. AB bloodtype)

3. Incomplete dominance - dominant allele does not completely hide recessive allele. (pink flowers{red and white})

4. Polygenetic inheritance - many genes controlling one physical characteristic (trait)(ex. eye skin color)

5. Pleiotrophy - one gene controlling many physical characteristics (SRY gene in males)
Term
punnett square
Definition
prediction of both genotype and phenotype of offspring;
Term
monohybrid cross
Definition
punnett square that looks at one physical characteristic;
Term
dihybrid cross
Definition
looks at (predicts) two traits;
Term
recessive allele disorders
Definition
disorders caused by recessive alleles; individual must have two recessive alleles to display disorder;
Term
carrier
Definition
hederozygote that will not display the disorder


ex. sickle cell trait
Term
dominant allele disorders
Definition
disorders cause by dominant alleles; only needs one copy of the dominant allele to actually display the disease/disorder;
Term
sex-linked (sex chromosome disorders)
Definition
disorders carried on the sex chromosomes; (90% are located on the X chromosome)
Term
chromosome number disorders
Definition
too much or too little genetic information
Term
nondisjunction
Definition
failure of homologous chromosomes to seperate during meiosis.
Term
Trisomy 21
Definition
results from nondisjunction of autosomes; will have 3 copies of chromosome #21; reulst in an individual having down-syndrome;
Term
Turner Syndrome
Definition
nondisjunction in the sex chromosomes; females may only have one X chromosome; (XO)

These females are sterile and lack 2nd sexual characteristics;
Term
Trisomy X
Definition
nondisjunction in sex chromosomes; female will have 3 X chromosomes;
Term
Klinefelter Syndrome
Definition
nondisjuntion in sex chromosomes; male will have 2 X chromosomes and one Y (XXY); male will be sterile with mixed secondary sexual characteristics;
Term
Jacob Syndrome
Definition
nondisjunction in sex chromosomes; male with 1X and 2Y chromosomes (XYY); "normal"
Term
Two types of tumors:
Definition
benign - tumor tht will stay in place;

malignant - tumor has the ability to invade surrounding areas;
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