Unit B: Cell structure

Animal cell

Liver Cell

Cell membrane

Nucleus

Nucleus

Nuclear pores

FUNCTIONS OF NUCLEUS:

• Nuclear membrane/envelope bilayer, separates and contains nuclear contents (DNA).

• Nuclear pores: allow mRNA out of nucleus, nucleotides, nutrients & enzymes in. They are made from protein.

• Chromatin: Protein & DNA; form chromosomes when cell divides.

• Nucleolus:contains rRNA and Ribosomal proteins.

The Endoplasmic Reticulum: ER

• Rough E.R.

• Studded with ribosomes

• Site of protein synthesis for proteins meant for export

• Phospholipids made here

• Smooth E.R.

• Detoxifies poisons (found in liver cells)

• Synthesize steroids

Endoplasmic Reticulum

Endoplasmic reticulum

Ribosomes

Function of Ribosomes

• Made from two protein subunits and rRNA

• Some are free, found alone in cytoplasm

• Others are attached to the RER• Translation of mRNA into

polypeptides or PROTEIN SYNTHESIS!

Ribosome structure:

Mitochondria

Function of Mitochondria:

• Cellular Respiration converts energy in Glucose to ATP

• C6H12O6 + O2 CO2 + H2O + 38 ATP

• Found in large numbers in energetic cells (sperm cells, muscles etc.)

Golgi apparatus

Looks like a series of flattened sacules.

Appears close to the cell membrane.

Golgi•Packages, modifies and stores molecules.

•Forms transport or secretory vesicles

•Involved in export of proteins through exocytosis.

•Draw diagram page 2 in green book exocytosi.ram

Lysosomes

Lysosomes:

• Contain hydrolytic enzymes (help to perform hydrolysis) for digesting molecules.

• These special vacuoles merge with another molecule containing vacuole for cell digestion.

• Called “suicide sacs”, contents could destroy cell!

Microtubules, cytoskeleton

Cytoskeleton

• Many protein filaments (actin filaments and microtubules) help organize and anchor cell parts.

cilia

Cilia and flagella microtubule arrangement 9+2

Function of cilia and flagella:

Cilia:

•Line the respiratory passages and sweep mucus upwards.

•Line the oviducts to transport ovum to uterus

•Flagella: Propel sperm

towards the ovum.