The Cell

IV. Cell Differentiation and MORE about DNA

A. Specialization of cells

B. Apoptosis

1. Essential for survival

2. Improper regulation may play a role in diseases such as AIDS, cancer, Alzheimer=s, and rheumatoid arthritis (Sci. Amer., Dec. 1996)

C. Chromosomes = DNA and proteins

1. Function of DNA: 

2. Structure of DNA

a. Double stranded helix

b. Nucleotides

1. Phosphate group (an acid)

2. Deoxyribose sugar

3. Nitrogen base

c. Nitrogen Bases (over 3 billion base pairs/chromosome)

1. Adenine (A)

2. Thymine (T)

3. Cytosine (C)

4. Guanine (G)

d. Complementary base pairing

1. A bonds with T

2. C bonds with G

3. Genes = 

    Human Genome Project:  What is it?

    Apply your knowledge with an online article:  Implications of the Genome Project for Medical Science (click on "The Future of Research and Medicine")

C. RNA (compare and contrast with DNA in terms of structure and function):

1. Function: 

2. Structure

a. Single stranded (no helix)

b. Nucleotides

1. Phosphate group

2. Ribose sugar

3. Nitrogen base

c. Nitrogen bases

1. Adenine (A)

2. Uracil (U) - 

3. Cytosine (C)

4. Guanine (G)

3. Types of RNA and their roles in protein synthesis

a. Messenger RNA (mRNA)

b. Transfer RNA (tRNA)

c. Ribosomal RNA (rRNA)

D. Protein Synthesis

1.  Transcription

Where?

How?

Summary:

 

2.  Translation

Where?

How?

Summary:

 

We all start out as a single-celled organism. How do we become the multicellular organism we are today? What happens when our skin cells, for example, become damaged or just old?

Mitosis, also called cell division in multicellular organisms, is responsible for the growth and repair of body cells. Because all cells contain genetic material in the form of DNA, a cell cannot function properly unless it receives a full copy of its species' DNA. Where is the genetic material found in the cell?

Mitosis provides a way in which copies of DNA are passed from the so-called mother cell to 2 daughter cells.

Mitosis defined:  

Somatic cells

Reproductive cells

Definition of terms:

chromatin - The thin DNA molecules within the nucleus when cellular division is not occurring (i.e. during Interphase)

chromosomes - The highly coiled and condensed DNA molecules during the process of cellular division (During this time, the chromosomes can be photographed and counted. The chromosome number for humans is 46. This is the diploid (2N) number)

diploid - The 2N number of chromosomes that occurs in all cells of the body. It includes 2 chromosomes of each kind (one from mom, one from dad).

haploid - Half of the diploid number of chromosomes. It contains only one of each kind of chromosome (sperm and egg are haploid)

Cell division involves nuclear division (karyokinesis) and also division of the cytoplasm (cytokinesis). Before nuclear division occurs, DNA replicates and produces an exact copy of itself. These duplicate chromosomes are called sister chromatids and are genetically identical (they contain the same genes). The sister chromatids are attached to each other at a region called the centromere.

During nuclear division, the sister chromatids separate and each daughter cell receives one. Once the chromatids are called chromosomes and each daughter cell gets a complete copy of have separated, they the original cell's genetic material.

When a cell is not dividing, it is in Interphase. DNA replicates itself and is present as chromatin during this phase. It is during this phase that the cell is carrying out its usual daily metabolic functions.

THE STAGES OF MITOSIS (Use the models of each of the stages to take note of what characterizes each stage and be able to draw them out):

Prophase

Metaphase

Anaphase

Telophase

Last Updated 05/26/06

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