Structure and Function of the Cell

Chapter 4

4.1 Discovering the cell…

1665 – Hooke looked at plants under the microscope and saw little boxes– He named them “cells”

1673 – Van Leeuwenhoek was the first to see living cells

Fast Forward…150 years!

Schleiden – all plants are composed of cells

Schwann – all animals are composed of cells

Virchow – cells come only from other cells

These three scientists’ work lead to the modern CELL THEORY

The Cell Theory

1. All living things are composed of cells

2. Cells are the basic unit of an organism

3. Cells only come from the reproduction of preexisting cells.

Cell Diversity

Red Blood Cells Bacterial Cells

Parasitic CellUlcer causing bacteria cells

Your body has over 200 different types of cells!

Cell Size

Most cells are microscopic

Cell size is limited by the surface area tovolume ratio

Cell Shape

Shape is determined by the function of the cell

Internal Organization

Prokaryotic Vs. Eukaryotic Cells

“Before Nucleus”

No Nucleus or Membrane organelles

Single cell organisms

“True Nucleus”

Yes Nucleus and Membrane organelles

Multicellular and singleCell organisms

Surface Area to Volume Ratio

Surface Area : L x W x # of sides

Volume: L x W x H

Ratio : surface area/volume

Now you try….

1. Obtain a copy of the lab: Modeling Cells: Surface Area to Volume AND box paper

2. Cut out boxes and tape them together (3 boxes total)

3. Complete lab worksheet about surface area to volume ratio

All Eukaryotic Cells Have…

1. A cell membrane

2. A nucleus

3. Other organelles

Parts of the Eukaryotic Cell

The structures are determined by the functions of each part

1. Cell Membrane

Function: outer layer of a cell that allow substances into and out of the cell

Selectively permeable – allows only certain things to cross the membrane

Parts of the Membrane

Membrane Lipids– Phospholipids

arranged due to their hydrophobic and hydrophilic ends

– Lipid bilayer– Steroid

(cholesterol) embedded within

Parts of the Membrane (cont)

Membrane Proteins– Peripheral proteins

– attached to either side of the cell membrane

– Integral proteins – embedded within the cell membrane and extends out on both sides

Fluid Mosaic Model

Membrane behaves like a liquid– Lateral movement of lipids and proteins

Mosaic – changing pattern of proteins and lipids in the membrane

Organelles

“Mini organs” of the cell

Each organelle has its own structure and function

All cells have different types and numbers of organelles

Nucleus

Function: to store the hereditary information of the cell (DNA) and to control the cell

Contains: nuclear envelope, nuclear pores, nucleolus, and chromatin (chromosomes)

Mitochondria

Function: makes ATP

“Powerhouse of the Cell”

Location: highly active cells

Rough Endoplasmic Reticulum

Function: Makes proteins, glycoproteins, and membranes for export out of the cell

Covered in ribosomes Location: surrounds

nucleus in cells that produce many proteins

Smooth Endoplasmic Reticulum

Function: Makes lipids, metabolizes carbohydrates, and detoxification center for the cell

Location: abundant in liver, kidney, ovaries, and testes

Ribosomes

Function: Protein synthesis

Location: Attached to E.R. or free in cytoplasm

Made in nucleus and completed in cytoplasm

Golgi Apparatus Function:

Manufacturing, warehousing, sorting, and shipping materials out of the cell

Location: found in most cells

Lysosomes Function: Digests

(breaks down) macromolecules the are in the cell, such as proteins and carbs.

Also breaks down dead cells

Location: abundant in liver and white blood cells

Peroxisomes Function: Breaks

down fatty acids Detoxification

center in liver cells

Location: abundant in liver and kidney cells

Cytoskeleton

Function: Support system of the cell, aid in movement within the cell

3 Structural Types: microtubules microfilaments intermediate filaments

Cytoplasm

Function: Holds organelles in the cell

Site of all chemical reactions in cell

Location: contains organelles in cell

Cilia and Flagella

Function: Locomotion and movement of materials around the cell

Location: outside of cell

Animal cells only

Cell Wall

Function: Protects the cell, gives the cell shape and structural support

Plant cells

Chloroplasts Function:

Photosynthesis Makes energy from

the sun Location: “green

parts” of plant In plant cells

Central Vacuole

Function: Stores materials especially water and waste products

In plant cells