Cell Structure & Function

Cell TheoryAll living things are made up of cells.

Cells are the smallest working units of all living things.

All cells come from preexisting cells through cell division.

Definition of CellA cell is the smallest unit that is

capable of performing life functions.

ProkaryoticDo not have structures surrounded by membranes

Few internal structures

One-celled organisms, Bacteria

Eukaryotic

Parts of the Cell

All working together so that the cell can grow, work, repair, and

reproduce

• Outer membrane of cell that controls movement in and out of the cell

• Double layer

Surrounding the Cell

Functions of Plasma MembraneFunctions of Plasma Membrane Protective barrierProtective barrier

Regulate transport in & out of Regulate transport in & out of cell cell

Allow cell recognitionAllow cell recognition

Receptor proteins function in cell Receptor proteins function in cell communication communication

Contains the cytoplasm (fluid in Contains the cytoplasm (fluid in cell)cell)

Provide a binding site for Provide a binding site for enzymesenzymes

Homeostasis

Structure of the Plasma Membrane

– Found around the cell, the nucleus, vacuoles, mitochondria, and chloroplasts.

– Embedded with proteins and strengthened with cholesterol molecules.

Membrane Proteins

Nucleus Directs cell activities

Contains genetic material - DNA

• Surrounds nucleus• Made of two layers• Openings allow material to

enter and leave nucleus

Separated from cytoplasm by nuclear membrane

Inside the nucleus

Endoplasmic Reticulum

Ribosomes

Each cell contains thousands

Found on ribosomes & floating throughout the cell

Mitochondria

Golgi Bodies

Proof reads proteins & makes minor corrections

Move materials within the cell

Move materials out of the cell

Lysosomes

‘Digests’proteins, fats, and carbohydrates

Transports undigested material to cell membrane for removal

Cell breaks down if lysosome explodes

Hydrolyticenzymes

Vacuoles

Also used for digestion, and waste removal

Contains water solution

Help plants maintain shape

Cytoplasm

Gel-like mixture -mostly water

Protects & stabilizes organelles

Surrounded by cell membrane

Cells break down food sources i.e. glucose, fats, and protein &release their stored energy.

Produce energy storage molecules called ATP – adenosine triphosphate.

If O2 is present following glycolysis, pyruvate is modified and enters the mitochondria.

Here food is broken down completely into CO2.

Energy storage molecules like NADH and ATP are produced.

Energy carriers like NADH drop off electrons

As the electrons “fall” to oxygen energy is stored in a payload of ATP.

Oxygen picks up electrons and hydrogen ions to form water.

ATP

ATP

ATP

Energy from

electrons

O2

H2O

ATP is constantly being used and remade in the cell.

Energy is released or stored by breaking or making a phosphate bond.

Summary of Cellular Respiration

Respiration

Process

Where Process Occurs

Net Gain of ATP

Per Glucose

Anaerobic Glycolysis & Fermentation

Cytoplasm 2 ATP

Aerobic Krebs Cycle and Electron

Transport

Mitochondrion 36 ATP

Phospholipid Bilayer

Passive Active

Along the concentration gradient

NO NET MOVEMENT OF H2O (equal amounts entering & leaving)

Molecules are moved out of the cell by vesicles that fuse with the plasma membrane.

This is how many hormones are secreted.

Active Transport

Pinocytosis

Most common form of endocytosis.

Takes in molecules dissolved in H2O.

Phagocytosis

Ingestion of solid particles by endocytosis

Fuses with lysosomes and the material is degraded