Unit 3 - Cells I. Cytology - The study of cells A. Cell Theory 1. Cells are the basic unit of structural units of all plants and animals. 2. Cells are the smallest functioning units of life. 3. Cells are produced by the division of pre-existing cells. 4. Each cell maintains homeostasis.
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Unit 3 - Cells I. Cytology - The study of cells A. Cell Theory 1. Cells are the basic unit of structural units of all plants and animals. 2. Cells are.
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Unit 3 - Cells
I. Cytology - The study of cellsA. Cell Theory
1. Cells are the basic unit of structural units of all plants and animals.
2. Cells are the smallest functioning units of life.
3. Cells are produced by the division of pre-existing cells.
4. Each cell maintains homeostasis.
B. Ways we visualize cells:
1. Light microscopes – 1000X, thin sections
2. Electron microscopes – 1oo,oooX
b. Scanning = 3-D, surface, plasma membrane
a. Transmission – very thin sections, show detail of internal cellular structures
C. The typical cell – The cell membrane separates:
1. Extracellular (Interstitial) fluid – Watery medium surrounding the cell
2. Cytoplasm – cell contents made up of:
a. CYTOSOL – fluid inside
b. ORGANELLES – “little organs”, structures that perform specific functions
D. Membrane Transport - Selectively permeableAllows some materials to pass, prevents others (based on size, electrical charge, molecular shape, lipid solubility, or combination.)
1. PASSIVE - Move ions or molecules without an energy input, through the lipid portion of the membrane or through a channel protein.
EX: Osmosis - Diffusion of water across a selectively permeable membrane toward a solution that has the highest solute concentration (due to substances dissolved, etc. in solution)
Osmotic pressure – the amount of pressure required to stop osmosis across a membrane.
E. Protein Synthesis - Cells are protein factories – produce a large # of proteins, some structural, others regulatory (hormones), antibodies, enzymes
1. The genetic code -
DNA – Holds the instructions (genes) to produce a protein.
a. Made up of nucleotides that are in turn made up of a nitrogen base, phosphate, and deoxyribose sugar.
b. Exocytosis – elimination of undigestible particles.
b. Located in the nucleus of eukaryotic cells, cannot leave
c. Double-stranded molecule that is kept together by H-bonds between complementary base pairs.
2. Transcription - Instructions are copied from DNA.
a. From double-stranded DNA, which cannot leave the nucleus, the protein instructions are copied as complementary base pairs into single-stranded messenger RNA (mRNA). b. The mRNA leaves the nucleus through the nuclear pores to reach protein factories – WHICH ORGANELLE? WHERE LOCATED?
5. Cancer – cells duplicate without control•Tissue is called tumor, growth, neoplasm•Oncology – The study of•Cancerous is called malignant•Non-cancerous is benign – does not spread to other parts and may be removed
•Hyperplasia – increase in frequency of cell division
a. Malignant tumors – duplicate continuously, quickly and without control
•Hyperplasia
•Metastasis - Spread to other parts, cancer cells secrete AMF (autocrine motility factor) – a protein which allows them to metastasize – hard to detect and eliminate
•Often this invasion kills the normal tissues by starving it out•Then they invade adjacent tissues and establish secondary tumors
b. Causes •CARCINOGEN - Chemical or environmental agent
that causes cancer (60-90% of human cancers) 90% of all lung cancers caused by smoking, UV radiation
•VIRUSES - Mostly in animals
•ONCOGENESIS - Genes found in human cells that trigger cancerous growth when inappropriately activated