BIO 50A- Ch. 3

Human cells ________

Vary in size, shape & function

Cell Structure:

1. Cell membrane

2. Nucleus

3. Cytoplasm

4. Cell Organelles

Cell membrane

Semi-permeable, phospholipids permit diffusion; cholesterol provides stability

Nucleus

Control center

Nucleus: form ribosomal RNA

Chromosomes: DNA & Protein genetic info. (Genome)

Cytoplasm

Watery solution site for reactions

Cell organelles

Intracellular structures with Specifc functions

Cellular transport Mechanisms

1. Diffusion

2. Osmosis

3. Facilitated diffusion

4. Active Transport

5. Filtration

6. Phagocytosis

7. Pinocytosis

Diffusion

Movement of molecules toward a less concentrated area; Oxygen & CO₂ in cells

Osmosis

water moving to a area with less water

Facilitated diffusion

Transports cells that cannot self-diffuse

Active Transport

ATP moving substance to more concentration; nerve and muscle contain sodium pumps for ions

Filtration

Pressure forces water & dissolve materials through membrane

Phagocytosis

Moving cells engulfed in something; white blood cells

Pinocytosis

Stationary cells engulf small molecules; kidney tubule cells

Genetic Code

1. DNA

2. RNA

3. tRNA

4. Translation

5. Expression of genetic code

DNA

A-T and G-C, triplet code for amino acids

RNA

Transcription, mRNA copy of DNA nucleus —→ ribosomes

tRNA

anticodons on mRNA

Translation

tRNA brings amino acids to ribosomes

Expression of genetic code

DNA —→ RNA —> Proteins —→ hereditary

Genetic disease (Malfunction during copying)

Cell division

1. Mitosis

2. Meiosis

Mitosis

1 cell to 2 cells (DNA Replication)

Prophase, Metaphase, anaphase, and telophase( cytokinesis is a division)

Essential for growth (permanent loss in adult cells)

Meiosis

Divides cells into 4

Oogenesis: ovaries form egg cells

Spermagenosis: testes

Fertilization: restores diploid number