Chapter 7Cell Structure

and Function

Life is Cellular

The Cell Theory Anton van Leeuwenhoek-1600’s One of the first people to use a

microscope to study organism in pond water

Made detailed drawings of the organisms

Robert Hook -1665

Uses 1st light microscope to look at thin slices of plant tissue(cork)

Notices it was made of thousands of tiny chambers

Called them “Cells” Cells- basic units of all forms of

life

Under the microscope: drawings of the instruments used by Robert Hooke (left) and the

cellular structure of cork according to Hooke (right) (reproduced from Micrographia, 1665).

Matthais Schledian - 1838 All plants are made of cells

Rudolf Virchow – 1839 All animals are made of cells Summarized his research by saying

“Where a cell exist, there must have been a preexisting cell”

Cell Theory All living things are

composed of cells Cells are the basic units of

structure and function in all living things

New cells are produced from existing cells

Basic Cell Structures

Despite differences in sizes and shapes, certain structures are common to most cells

All cells have a cell membrane and a cytoplasm

Plants Cells Slide Show by StudyJams 

The cells of plants include several parts, such as the cell body, cytoplasm, mitochondria, nucleus, vacuole, cell wall, and cholorplasts.  Only plant cells have plant cell walls and chloroplasts.  Learn more about the plant cell with these detailed images from StudyJams.  The pictures are set to music with information written under each photo.  A short, self-checking quiz and song are also included on this link.

http://watchknowlearn.org/Video.aspx?VideoID=30845

Cell Membrane A thin, flexible barrier

around the cell Support, Protection, Interaction with environment

Cytoplasm All the material inside

the cell membrane except the nucleus

Contains many different structures known as organelles

Cytoplasm

Nucleus A large structure that contains the cells genetic material and controls the cells activities

Cell Wall A stronger, less flexible

layer around the perimeter of the cell

Found in plants Support, Protection, Interaction with environment

Prokaryotes and EukaryotesBiologist have divided cells into these 2

categories

PROKARYOTES EUKARYOTES Cell Membranes Cytoplasm No Nucleus Bacteria are

example Grow, Reproduce,

Respond to Environment

Cell Membranes/Walls

Cytoplasm Nucleus Organelles-

perform important cellular functions

Some are single celled, some are multicellular

Plants, animals, fungi are examples

Cell Structures Cell Wall

Found in plants, fungi, and nearly all Eukaryotes Not found in animal cell Lies outside the cell membrane Allow H2O, O2, CO2, and other substances to pass

through them Main function is to provide support and protection for the

cell Made from fibers of carbohydrates and protein

Produced in the cell and released at the surface to build wall

Plant cell walls are made mostly of cellulose Tough carbohydrate fiber Primary component of wood and paper

Nucleus Controls cell processes and

contains hereditary information in the form of DNA

All plant and animals cell contain nucleus

Contains nearly all of the cells DNA (except Mitochondrial DNA)Coded instructions for making proteins

Main function of the cell

Nucleus

Chromatin Is the granular material

visible within the nucleus

Consist of DNA bound to proteins

Spaghetti on a plate

Chromatin

Chromosomes Are the condensed form

of chromatin Distinct, threadlike

structures containing genetic info that is passed on from one generation of cells to the next

Chromosomes

Nucleolus Small dense region of

nucleus where ribosome assembly begins

Ribosomes aid in production of protein in the cell

Nucleolus

Nuclear Envelope Double membrane layer

around the nucleus Covered with pores that

allow substances to pass into and out of the nucleus

RNA and other info carrying molecules pass through these pores

Nuclear Envelope

Cytoskeleton Network of protein

filaments, maintains cell shape, involved in cell movement, made up of microtubules and microfilaments

Cytoskeleton

Microtubules Hollow tubes of protein Maintain shape Act as tracks for organelle

movement inside the cell Help separate chromosomes in cell

division, formation of centrioles in animal cells

Bundles of microtubules in some cells form cilia and flagella to provide cellular movement

Microfiliments Long, thin fibers that function in

movement and support of cell Much narrower than microtubules Extensive networks in cells Tough, flexible support Movement of organelles Motor proteins attach to organelles and

generate force to move organelles along the cytoskeleton

Organelles in The Cytoplasm“Little Organ”

Ribosomes Produce proteins Small particles of RNA and

proteins assembled in the nucleus

Endoplasmic Reticulum Components of the cell membrane are assembled and proteins are modified

PROTEIN SYNTHESIS IN

ROUGH ER

LIPID SYNTHESIS IN

SMOOTH ER

Called “Rough” because of ribosome's attached to the surface

Called “ Smooth” because of lack of ribosome's on the surface

Golgi Apparatus

Enzymes attach lipids and carbohydrates to proteins here

Proteins move here from ER Proteins are sent to their

final destinations from here

Lysosomes Break down lipids,

carbohydrates, and proteins from food particles to be used by the rest of the cell

Break down organelles that have outlived their usefulness

Remove debris from cell

Vacuoles Store materials (water, carbs,

proteins) Sac-like structures Plant cells have 1 central large

vacuole filled with liquid to support heavy structures such as leaves and flowers

Sometimes called vesicles

Chloroplast• Found mostly in plants•Use sunlight to make energy rich

foodmolecules in a process known as

photosynthesis•Bound by 2 photosynthetic

membranes that contain Chlorophyll (a green pigment in plants)

Chlorophyll

Mitochondria Release stored energy from food particles

in the cell Powerhouse of the cell Use energy from food to make high

energy compounds that the cell can use to power growth, development, and movement

Has 2 membranes (Inner membrane is folded)

Found in nearly all eukaryotic cells

Organelle DNA Mitochondria and Chloroplasts contain their own DNA that is

essential for their normal function and

growth

Endosymbiotic Theory Suggest that these organelles are

descendants of ancient prokaryotes They formed relationships with eukaryotic

cells that benefited them both Over time, the nuclear DNA took over cell

function and the organelle DNA became a remnant of their ancestors

In humans, we only inherit our mitochondria from our mothers!

Click on the HouseThe Cell as a Factory Read Page 182

Click icon to add picture

See Chart on page 183 – “A Comparison of Cells”

Movement through The Membrane

Cell Membrane Regulates what enters and

leaves the cell, provides protection and support

Takes in H2O and food and eliminates waste through the membrane

The Core of the Membrane is a Lipid Bylayer

Formed when certain kinds of lipids are dissolved in H2O

Each layer is composed of lipids with a hydrophilic head and hydrophobic tail

Tough, flexible barriers between the cell and its surroundings

Contain protein molecules that run through the layer

Form channels and pumps to help move materials across the membrane

Carbohydrate molecules attach to the outer surfaces of the proteins Act as chemical ID cards helping cells to

identify each other

The Core of the Membrane is a Lipid Bylayer

Diffusion One of the Most Important Functions of

the Cell Membrane is to control the movement of molecules from one side of the membrane to the other

The Concentration of a solution is the mass of the solute in a given volume of solution…mass/volumei.e 12 grams of salt dissolved in 3

liters of water is 12g/3L or 4g/L In a solution , molecules move

constantly, collide, and spread out randomly … they try to distribute evenly

Diffusion The movement of molecules from an area

of higher concentration to an area of lower concentration is known as Diffusion

When the concentration of a solute is the same throughout a solution, they system has reach Equilibrium

A solute will always try to establish a state of equilibrium

Diffusion causes substances to move across the membrane but does not require energy to do so

How Diffusion WorksThis animation shows the

Purple Molecules diffusing throughout the box.

Here the molecules move out of the liquid

and into the air by Diffusion

OsmosisIs the movement of water across a selectively

permeable membrane

Permeable Membranes allow all substances to cross

Impermeable Membranes do not allow any substances to cross

Selectively Permeable membranes only allow selected substances to cross

Osmosis

Isotonic A solution that is

equilibrium Same strength….same

concentration of solute and water

Isotonic

Hypertonic A solution that is said to

have a higher concentration of solute (less water per solute)

Above strength

Hypertonic

Hypotonic A solution that said to

have a lower concentration of solute (more water per solute)

Below Strength

Hypotonic

Osmotic Pressure A pressure exerted on the

hypertonic side of a selectively permeable membrane

Cells are filled with various molecules…salts, sugars, proteins, etc. therefore are Hypertonic to fresh water

Osmotic Pressure Water should move into the cell Cell should swell Most cells are bathed in isotonic fluids

such as blood that have concentrations of dissolved materials roughly equal to that inside the cell

Plant cells and bacteria that come into contact with fresh water have cell walls to help prevent them from expanding

Other cells use a mechanism to help pump out the excess water that is forced in by osmosis

Osmotic Pressure

The Diversity of Cellular Life

Unicellular OrganismsSingle celled organismsThey grow, respond to the

environment, and reproduce Include both prokaryotes and

eukaryotesBacteria (prokaryotes) and yeast

(eukaryotes) are examples Some live alone some live in

colonies

The Diversity of Cellular Life Multicellular Organisms

Cells do not ever live alone Cells are Interdependent; each has a function

that contributes to the fitness, or survival, of the organism

Have Cell Specialization Cells in multicellular organisms are specialized

to perform specific functions within the organism

Some created movement (muscle cells), some relay information (neurons), some produce enzymes (pancreatic cells, liver cells, gallbladder cells), etc

Levels of OrganizationA Multicellular organism from smallest to largest (most simple to most complex)

Cells

Tissue

Organs

Organ System

Cells Diversity of labor among

cellsBlood cells, nerve cells, muscle cells, etc

Specialization and Interdependence

TissuesA group of similar cells that perform a similar

function There are 4 Main types of tissue

(Muscles, Epithelial, Nervous, Connective) Epithelial Tissues cover or line body surfaces Connective Tissue include bone, blood,

cartilage and lymph Muscle Tissue controls the internal movement

of materials in the body, as well as external movement of the entire body or body parts

Nervous Tissue receives messages from the body’s external and internal environment, analyzes the data, and directs the response

Organs Many groups of tissues that

work together Each muscle in the body is and organ, although there are muscle tissue, nervous tissue (nerve endings and neurons), and connective tissue (cartilage, tendons, ligaments, blood) present in each muscle

Organ System A group of organs that works

together to perform a specific function and complete a series of specialized tasks.

There are 11 major organ systems in the human body

Chapter 7 Bellwork page 169-173

1. What does the Cell Theory State? 2. Explain the difference between Cell Wall

and Cell Membrane. 3. What is the main function of the Cell

Wall? 4. What is the main function of the

Nucleus? 5. Compare and Contrast Prokaryotes and

Eukaryotes. 6. What is the difference between

Chromatin and Chromosomes?

Chapter 7Bellwork page: 176-189

1. What are the functions of: A. Endoplasmic Reticulum B. Golgi Bodies C. Ribosomes D. Chloroplast E. Mitochondria 2. Where do we think mitochondrial DNA comes from? 3. Describe 2 main differences between Prokaryotic and

Eukaryotic Cells. 4. Describe a Lipid Bylayer. 5. Explain the process of diffusion. 6. What is Osmosis? 7. Explain the difference between isotonic, hypertonic, and

hypotonic. 8. What is facilitated diffusion? 9. Describe Active Transport.

Warm- Ups # 3 Pages 190-197

1. Explain the difference between unicellular and multicellular.

2. What is cell specialization? 3. What are the 4 levels of organization? 4. What are the 4 main types of tissue? 5. What is the difference between an

organ and an organ system?