Lecture 3 & 4 – Cells & Metabolism

What is the membrane made of?

phospholipid bilayer

selectively permeable

fluid mosaic

What is the structure of the phospholipid bilayer

Hydrophilic head

Hydrophobic tails

Why does the structure of the phospholipid bilayer matter?

only lipid soluble (non-polar) substances can pass directly

What are some things that can pass through the phospholipid bilayer?

O2, CO2, Steroid hormones

What cannot pass easily through the phospholipid bilayer

Glucose, ions, proteins

What does cholesterol provide for the membrane

stability

How does cholesterol work in the membrane

at high temps it prevents too much fluidity

at low temps it prevents freezing

List 5 functions of membrane proteins.

Channels, carriers, receptors, enzymes, cell adhesion/recognition (CAMs).

What disease results from defective chloride channels?

Cystic fibrosis

What are the two types of transport across the membrane

Passive (no ATP) and Active (requires ATP)

What is Passive transport?

movement down gradient

What is diffusion

movement from high concentration to low concentration

What factors affect diffusion

Concentration gradient

distance

temperature

size of molecule

What is facilitated diffusion

A type of passive transport where substances mover across the cell membrane through a protein without using ATP

When does facilitate diffusion occur?

Molecule cannot pass directly through the lipid bilayer

moves down its concentration gradient

uses a membrane transport protein

What are the two types of proteins involved in facilitated diffusion

Channel proteins and carrier proteins

What is osmosis

Movement of water across a semipermeable membrane

What is osmolarity

Total concentration of solute particle s

What is tonicity

effect of solution on cell volume

What does isotonic mean?

same solute concentration

Hypertonic

cell shrinks

Hypotonic

cell swells

Anabolism does what

Builds complex molecules from smaller ones and requires energy

Catabolism does what?

Breaks larger molecules in smaller ones and release energy

What is metabolism

the sum of all the chemical reactions occurring in the body to maintain life

Two major steps of protein synthesis?

Transcription and Translation

Where does transcription occur

in the nucleus

What happens during transcription

DNA double helix unzips

one strand acts as a template

RNA polymerase builds complementary RNA strand

What is made due to transcription

mRNA

Where doe translation occur

in the cytoplasm at the ribosome

What happens during translation

mRNA attaches to ribosome

The ribosome reads mRNA in groups of 3 bases

Transfer RNA brings matching amino acids

Amino acids link together to form a polypeptide chain

Codon

3-base sequence on mRNA

Anticodon

matching sequence on tRNA

Start codon

AUG

Interphase

• Growth

• DNA replication

Mitosis

Nuclear division

Cytokinesis

Cytoplasm division

Atrophy

cells shrink

hypertrophy

cells grow bigger

hyperplasia

more cells

dysplasia

abnormal shape

neoplasm

new growth

necrosis

cell death from injury

apoptosis

programmed death