Chapter 7Cell Structure and Functions

Chapter Outline

• 7-1 Life is Cellular

• 7-2 Eukaryotic Cell Structure

• 7-3 Cell Boundaries

• 7-4 The Diversity of Cellular Life

Microscopes and Scientists1. 1665 Robert Hooke

– used compound microscope to look at cork (dead wood)

– called small chambers “cells”

2. Anton Van Leeuwenhoek: used single lens microscope & saw tiny organisms in pond water

Microscopes and Scientists

3. Mathias Schleiden: concluded that plants are made of cells

4. Theodore Schwann: concluded that animals are made of cells

5. Rudolph Virchow: stated cells come from existing cells

The Cell Theory

• All living things are composed of cells.

• Cells are the basic units of structure and function in living things.

• New cells are produced from existing cells.

Exploring the Cell 1. Electron microscopes

• Samples are put in a vacuum… must be dead

• Transmission electron microscopes (TEM): beams of electrons are

passed through a thin sample

• Scanning electron microscope (SEM): beam of electrons move over the surface of a sample

Prokaryotes and Eukaryotes

1. All cells have a cell membrane and contain DNA

2. nucleus: a large structure that contains the cell’s genetic material in the form of DNA

3. Prokaryotes: cells that do not contain a nucleus– Small and simple cells– Bacteria are prokaryotes

Prokaryotes and Eukaryotes

Prokaryotic Cell

Cell membrane

Cytoplasm

Nucleus

Organelles

Eukaryotic Cell

Cytoplasm

Cell membrane4. Eukaryotes: cells that contain a nucleus

– Large and complex cells; Highly specialized

– Can be unicellular (one celled organism) or multicellular

– Plants, animals, fungi and protists are eukaryotes

Cell Organelles1. Eukaryotic cells contain organelles: specialized

structures that perform functions within the cells

2. Cytoplasm portion of cell outside the nucleus

3. Nucleus control center of the cell

4. Chromatin DNA bound to protein

5. Chromosomes condensed form of chromatin seen during division

Cell Organelles6. Nucleolus dense region in nucleus where

ribosomes are made

7. Ribosomes make proteins with instructions from the nucleus

8. Endoplasmic Reticulum

site where lipids, proteins and other materials are made; two types- smooth and rough

9. Golgi Apparatus

modifies, sorts, and packages proteins and materials

10. Lysosomes organelle filled with enzymes that breakdown wastes

Cell Organelles11. Vacuoles structure that stores water, salts,

proteins, and carbs

12. Mitochondria convert energy from food into compounds the cell can use

13. Cloroplast capture energy from sunlight and covert to chemical energy

14. Cytoskeleton network of proteins that maintains cell shape and helps in cell movement

15. Centrioles organelle that helps in cell division in animal cells

Do now – vocab review• ________________ = basic unit of life

• ________________ = DNA bound to protein• ________________ = cells that contain a

nucleus

• ________________ = specialized structures found in some cells

• ________________ = mass of solute in a given

volume of solution

Bonus Question

• What is the term that describes the movement of the smell of popcorn?

Cell BoundariesCell membrane: thin flexible barrier that regulates what

enters and leaves the cell.

1. Most cell membranes have a lipid bilayer

2. Contain proteins and carbohydrates

Outsideof cell

Insideof cell(cytoplasm)

Cellmembrane

Proteins

Proteinchannel Lipid bilayer

Carbohydratechains

Lipids and water

• http://telstar.ote.cmu.edu/Hughes/tutorial/cellmembranes/orient2.swf

Cell Boundaries

Cell Wall: provides support and protection1. Present in plants, algae, fungi and many prokaryotes2. Cell walls lie outside the cell membrane3. Composed mostly of a carbohydrate called cellulose

Nuclearenvelope

Ribosome(attached)

Ribosome(free)

Smooth endoplasmicreticulum

Nucleus

Rough endoplasmic reticulum

Nucleolus

Golgi apparatus

Mitochondrion

Cell wall

CellMembrane

Chloroplast

Vacuole Plant Cell

Diffusion through boundaries

1. concentration = mass of solute in a given volume of solution

– Ex: 12 g salt in 3L water = 4g/L

2. diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration

3. equilibrium: when concentration of solute is same throughout area

Diffusion video

Diffusion visual

• website

Osmosis4. Osmosis: diffusion of water across a selectively

permeable membrane

– Water can move across the membrane, and many solutes cannot

Osmosis– Terms for concentrations on sides of a

membrane

• Isotonic: concentration is same on both sides

• Hypertonic: concentration of solute is higher

• Hypotonic: concentration of solute is lower

– Cells are usually near isotonic solutions, so that they do not burst

5. Facilitated Diffusion: protein gates help certain molecules diffuse

HighConcentration

LowConcentration

CellMembrane

Glucosemolecules

Proteinchannel

6. Active transport: uses energy to move molecules from an area of low concentration to high concentration

Animation

Normally cells have a lower Na+ concentration than outside. To keep it that way, cells have to pump Na+ out of the cell.

Molecule tobe carried

Moleculebeing carried

Energy

• Endocytosis: process of taking material into cells by forming a pocket of cell membrane– Phagocytosis – surrounding food particles– Pinocytosis – surrounding liquids

• Exocytosis: process of releasing materials

Review of Cell transport

• Wiley.com

Label the organelles

Unicellular vs. Multicellular1. unicellular organisms: one-celled organism: yeast,

volvox aureus

2. multicellular organisms

– Cell specialization: cells throughout an organism can develop in different ways to perform different tasks

– Specialized animal cells

• Red blood cells – carry oxygen throughout body

• Pancreatic cells – many ribosomes to make proteins and enzymes for digestion

• Muscle cells – overdeveloped cytoskeleton

Multicellular organisms

Levels of organization (Individual organism)– Cellstissuesorgansorgan systems

Muscle cell Smooth muscle tissue Stomach Digestive system