Cell Structure & Function

Cell Theory• All 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.

• Cells are small so they can exchange materials with their surroundings.

Definition of Cell

A cell is the smallest unit that is capable of performing life

functions.

Examples of CellsAmoeba Proteus

Plant Stem

Red Blood Cell

Nerve Cell

Bacteria

Two Types of Cells

•Prokaryotic

•Eukaryotic

Living cells classified into 2 different types based on internal structure

• Prokaryotic cells – little defined internal structure. Lack a clearly defined structure to house their DNA. Organisms made up of prokaryotic cells are called Prokaryotes (all bacteria, all archaeans)

• Eukaryotic cells – more complex structure. Contain many different kinds of membrane-bound structures called organelles suspended in cytosol.

Types of Cells

REVIEW• What are the main differences between

Prokaryotic and Eukaryotic cells?• List one key point from the cell theory• What is the definition of a cell?• Why does a small cell have more surface

area to volume?

Prokaryotic• Do not have

structures surrounded by membranes

• Few internal structures

• One-celled organisms, Bacteria

Prokaryotic Cells• Prokaryotic cells include the bacteria and

archaea.

• Bacterial cells have these constant features:• Outer Boundary: Cell wall• Plasma membrane• Cytoplasm: Ribosomes• Thylakoids (Cyanobacteria)• Many enzymes• Nucleoid: Chromosome (DNA only)

Eukaryotic Cells

• Eukaryotic cells have a nucleus that controls the workings of the cell.

• All cells are surrounded by a plasma membrane made of phospholipids and proteins.

Eukaryotic• Contain organelles surrounded by membranes• Most living organisms

Plant Animal

• The plasma membrane regulates what enters and exits the cell.

• Inside the plasma membrane, the nucleus is surrounded by cytoplasm.

• Cytoplasm is a semi-fluid medium.

• Plant cells have a cell wall in addition to the plasma membrane.

• Primary cell walls are made from cellulose. The secondary cell wall, which forms inside the primary wall, is formed from lignin. Its purpose is to give strength to the cell.

REVIEW• List one main difference between plant

and animal cells• Do plant and animal cells have

organelles?• What is the function of organelles?

Animal cell anatomy

“Typical” Animal Cell

Plant cell anatomy

“Typical” Plant Cell

REVIEW• What are the main similarities and

differences between plant and animal cells?

Cell PartsOrganelles

• Animal and plant cells have organelles.

• Organelles compartmentalize functions within the cell.

• The organelles of animal and plant cells are similar to each other except that centrioles are present only in animal cells, and chloroplasts are present only in plant cells.

Surrounding the Cell

Cell Membrane

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

• Double layer

Cell Wall• Most commonly found

in plant cells & bacteria

• Supports & protects cells

REVIEW• Which structure surrounds a cell?• Briefly outline the cell theory

Inside the Cell

Nucleus

• Directs cell activities• Separated from cytoplasm by nuclear

membrane• Contains genetic material - DNA

Nuclear Membrane• Surrounds nucleus• Made of two layers• Openings allow

material to enter and leave nucleus

Chromosomes• In nucleus• Made of DNA• Contain instructions

for traits & characteristics

Nucleolus• Inside nucleus• Contains RNA to build

proteins

Cytoplasm• Gel-like mixture• Surrounded by cell membrane• Contains hereditary material

Endoplasmic Reticulum• Moves materials around

in cell• Smooth type: lacks

ribosomes• Rough type (pictured):

ribosomes embedded in surface

Ribosomes• Each cell contains

thousands• Make proteins• Found on rough

endoplasmic reticulum & floating throughout the cell

Mitochondria• Produces energy through

chemical reactions – breaking down fats & carbohydrates

• Controls level of water and other materials in cell

• Recycles and decomposes proteins, fats, and carbohydrates

Golgi Bodies• Protein 'packaging

plant'• Move materials within

the cell• Move materials out of

the cell

Cilia and flagella• Cilia and flagella - 9 + 2 pattern of

microtubules• Involved in movement (cell, eggs,

debris)

• Each cilium and flagellum has a basal body at its base.

Structure of a flagellum or cilium

Lysosome• Digestive 'plant' for

proteins, fats, and carbohydrates

• Transports undigested material to cell membrane for removal

• Cell breaks down if lysosome explodes

Vacuoles• Membrane-bound

sacs for storage, digestion, and waste removal

• Contains water solution

• Help plants maintain shape

Chloroplast• Usually found in plant

cells• Contains green

chlorophyll• Where

photosynthesis takes place

REVIEW• List 5 structures within a cell• What do golgi do?• What does the mitochondria do?• What is the function of the cytoplasm?• What is the function of the nucleus?• What does the nuclear membrane allow to happen?• What is the function of the nucleolus?• What is the function of the lysosome?• What is the function of the endoplasmic reticulum?• Why don’t animal cells contain chloroplasts?