Biology notes 10-16-07 through 10-29-07
10-16-07
1953 Three scientists that discovered the DNA molecule
James Watson
Francis Crick
Maurice Wilkens
DNA strand
Deoxyribonucleic Acid
2 Purines
Adenine (pairs with Thymine)
Cytosine (pairs with guanine)
2 Primidines
Thymine (pairs with Adenine)
Guanine (pairs with cytosine)
1 Purine pairs up with 1 primidine to from a strand of DNA *see
sketch
The DNA contains strands of proteins
The ribosomes head off the codones across the space and proteins are
made
RNA strand
Nucleolus *see sketch
Spherical, single pore bear
Minute round body in the nucleus
It contains proteins and RNA
Ribonucleic Acid
The RNA is a copy of a segment from the DNA molecule
Function of the nucleolus: makes RNA
Strand of RNA *see sketch
Uracil replaces thymine in RNA
Uracil is the new primidine
2 Purines
Adenine (pairs with Uracil)
Cytosine (pairs with guanine)
2 Primidines
Uracil (pairs with Adenine)
Guanine (pairs with cytosine)
The nucleolus synthesizes (makes) and stores RNA until it moves out
of the nucleolus and into the cytoplasm, and there some of it becomes
part of the ribosomes.
Drugs: This can screw up the chromosome mapping and DNA and
RNA mapping of new generations of humans being produced. So BE
AWARE!
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Biology notes 10-16-07 through 10-29-07
10-17-07
One human cell contains 2-3 million genes. These genes are attached
to the chromosomes. They are composed of protein units.
Genes make up our hereditary traits. (Our genetic make-up)
Chromosome Numbers
Pairs
Man
23
Frog
13
Cat
19
Chicken
39
Earthworm
18
House Fly
6
Garden Pea
7
Onion
8
Redwood Tree
11
Horse
32
Carrots
9
Oak Tree
12
Rat
21
Tomato
12
Goldfish
47
Shrimp
127
Total Number
46
26
38
78
36
12
14
16
22
64
18
24
42
24
94
254
Chromosomes consist of genes and genes determine all potentialities
of a cell.
A gene is a segment of a gene molecule.
CELL MITOSIS
This is a process of cell division.
The Five stages of Mitosis: I Promised Mom A Tiger
1. INTERPHASE- Growth phase, resting phase, duplicating phase,
puffy and bloated.
2. PROPHASE-chromosome material doubles and becomes
threadlike; centrioles move apart from each other
3. METAPHASE- separation of chromatids.
4. ANAPHASE-chromatids move to opposite poles
5. TELOPHASE- final stage of mitosis; two daughter cells are
forming
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Biology notes 10-16-07 through 10-29-07
After 20 successive cell divisions, a single cell will produce 1,048,576
cells.
*See Cell Division Handout
Mitosis: how cells divide
Meiosis: how sex cells divide
10-29-07
How the materials pass in and out of the cell is called the
transportation process.
The two processes that carry on this transportation process is as
follows:
A. physical processes
a. diffusion
b. osmosis
c. filtration
B. physiological processes
a. active transport
b. phagocytosis
c. pinocytosis
The energy that powers any physiological process comes from
chemical reactions which take place in living cells. Therefore these 3
processes can only move substances through cell membranes as long
as the cells are alive and functioning.
When cells die the physiological processes cease (stop).
In the physical processes of diffusion, osmosis, and filtration, they go
on after cellular death occurs.
Diffusion: A process of even scattering or spreading of molecules and
ions through matter.
In a liquid: diffusion occurs in an even scattering from the solvent to
the solute.
Net Diffusion: of the solute in one direction and the solvent in the
other direction will eventually result in equilibrium. *see sketch
Our lives depend on diffusion.
The oxygen that we breathe enters our cells by diffusion through their
membrane walls.
Diffusion examples: Human gas, perfume, alcohol pads
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Biology notes 10-16-07 through 10-29-07
Gases diffuse across membrane walls
Osmosis: It is the movement of water through a semi-permeable
membrane.
If the membrane is not full permeable to all the solute particles then
equilibrium can not be reached. *see sketch
Water osmosifies across membranes
Gasses diffuse across membranes
Filtration: It is a physical process by which water and solutes pass
through a membrane when the hydrostatic pressure is unequal on each
side of the membrane.
Hydrostatic pressure means the force or weight of a liquid
pushing against some surface.
Filtration will occur when the pressure is greater on one side of the
membrane than the other.
Example: water, it will filter out of a solution which has high
pressure and into and area where there is low pressure.
Filtration occurs in only one direction from an area of greater pressure
to an area of lower pressure.
Active Transport: A built in device that moves molecules or ions
through cell membranes in an uphill direction or against their natural
pressure gradients.
Active transport mechanisms pump various substances though cell
membranes through cell membranes like sodium (Na) ions
Phagocytosis: a process by which a segment of cell membrane forms
a pocket around a bit of solid outside the cell, and breaks it off from
the rest of the membrane and moves it into the cell and ingest the
particles of the cells.
Only occurs in one direction: Inward
Eating process
Pinocytosis: a process by which a segment of cell membrane forms a
small pocket around a bit of fluid outside the cell, breaks it off from
the rest of the membrane and dissolves it in the cell.
Drinking process
2 processes of cell metabolism
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Biology notes 10-16-07 through 10-29-07
Catabolism: a breakdown of food compounds or of protoplasm into
simpler substances.
Anabolism: synthesis by cells of complex compounds (hormones,
vitamins) from simpler compounds like amino acids, simple sugars,
fats and minerals.
THE END!!
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