Chapter 2- The Cell

Life Science

7th grade

BELL WORK CH2 L.1• Cell theory:

– All living things are made of cells – Cell is the smallest unit of life – All cells arise from preexisting cells

• Macromolecule:– Form by joining many small molecules together. – Four kinds: nucleic acid, protein, lipid and carbohydrate.

• Nucleic Acid:– (macromolecule) Formed by nucleotides joining together. Make up

DNA/RNA, contains genetic information.

• Protein:– (macromolecule) Long chain of amino acids used to make everything

in the cell. Contains carbon, oxygen, nitrogen, hydrogen and sometimes sulfur

• Lipid:– (macromolecule) Does not dissolve in water. Great barrier.

• Carbohydrate:– (macromolecule) Made up of sugars. Made up of carbon, oxygen and

hydrogen. Main source of energy for the cell.

Lesson 1: Cells and Life

• Understanding cells– Microscopes allow us to see small things,

like cells.– Robert Hooke built microscope 300 years

ago• Looked at tree bark

– Honeycomb structure

• Small spaces looked like little rooms monks lived in called cells

Light vs Electron Microscope

• Light: – Magnification up to

1000-2000 times– Can see living cells

• Electron: – Magnification up to 2

million times– Can’t see living cells

Important Scientists

• Matthias Schleiden: (German) looked at plant cells

• Theodore Schwann: (German) animal cells

• Rudolf Virchow: (German) cells already exist, they arise from previously existing cells

The Cell Theory

• All LIVING things are made up of cells

The Cell Theory

• The cell is the smallest unit of life– Unicellular vs multicellular

Budding yeast

(Saccharomyces cerevisiae)

Salmonella bacteria

The Cell Theory

• Cells arise from previously existing cells– Mitosis/Meiosis– Video

Basic Cell Substances• Many substances in cells made up of

smaller parts called macromolecules• Small subunits/molecules join to form

macromolecules

• Four kind of macromolecules in the cell– Nucleic Acids– Proteins– Lipids– Carbohydrates

Nucleic acids• Make up DNA/RNA=

contain genetic information– Passed on from parent to

offspring

• Nucleotides join to form nucleic acids

• Contain information to make everything in the cell including lipids, proteins and carbohydrates

Proteins

• Long chains of amino acids

• Used for just about everything in the cell

• Each protein has a unique function

• Protein made as a long chain and then folds to make unique structure

Lipids• Make up

membranes– Don’t mix with

water= good barrier

• Play a role in energy storage and cell communication

ONE STEP UP: KNOWING THAT

WATER IS EVERYWHERE INSIDE

AND OUTSIDE THE CELL, AND

LOOKING A THE STRUCTURE OF

THE LIPID BILAYER, WHAT DO YOU

THINK HYDROPHOBIC MEANS?

Carbohydrates• Made up of

sugar molecules

• Store energy– Sugars and

starches

• Provide structural support– Cellulose in

plant cells

• Communication between cells ONE STEP UP: SOMETIMES BABIES LEAVE PIECES OF

BREAD IN THEIR MOUTHS FOR LONG PERIODS OF TIME

BEFORE SWALLOWING, WHY DO YOU THINK THIS IS?

Basic Cell Substances• Water

– Main ingredient in any cell • +70% volume

– Inside cell • Part of cellular processes

– Outside cell• Insulates and protects

– Maintains homeostasis» stable environment

– Structure H2O• Positive H+• Negative O-

ONE STEP UP: WHY WILL AN UNOPENED CAN

OF SODA EXPLODE IF YOU LEAVE IT IN THE

FREEZER?

HOMEWORK

• Vocabulary words on flash cards– Memorize for quiz

• Outline Lesson 1

• Page 48. (Lesson 1 review)– Questions 1-10

BELL WORK CH2 L.2• Cell Membrane (Plasma Membrane (PM)) : Flexible covering that

protects the inside of a call from the environment outside the cell• Cell Wall: Stiff structure outside cell membrane that protects a cell

from attack by viruses and other harmful organisms• Cytoplasm: Liquid part of a cell inside the cell membrane; contains

salts and other molecules• Cytoskeleton: Network of threadlike proteins joined together that gives

a cell its shape and helps it move• Organelle: Membrane-surrounded component of a eukaryotic cell with

a specialized function• Nucleus: Part of a eukaryotic cell that directs cell activity and contains

genetic information stored in DNA• Chloroplast: Membrane-bound organelle that uses light energy to

make glucose (sugar) from water and carbon dioxide in a process called photosynthesis

Lesson 2: The Cell

• Cell shape and movement– Shape= function– Nerve vs blood cell

Erythrocyte (red blood cell) Nerve cell

ONE STEP UP: WHY DO YOU THINK RED BLOOD

CELLS ARE SHAPED THE WAY THEY ARE?

Cell Membrane

• Protective covering surrounding cell– Flexible

• Made mostly of phospholipids and proteins

Cell Wall• Stiff structure outside the cell membrane

• Found in: plant cells, bacteria, some protists and fungi

• Protects cells from attackers, helps retain shape and gives structural support

Cell Appendages• Used for

movement• Flagella

– Tail-like– Move cell

• Sperm

• Cilia– Short, hair-like– Move a cell

• Paramecium

– Move molecules away from cell

• Upper Respiratory tract

Cytoplasm and Cytoskeleton• Cytoplasm= fluid in

the cell that contains salts and other molecules (also contains cytoskeleton)

• Cytoskeleton= network of threadlike proteins that are joined together– Provides shape

and movement

Cell Types• Eukaryote vs

Prokaryote– Prokaryotes=

usually unicellular• NO MEMBRANE

BOUND ORGANELLES

• Circular DNA

– Eukaryotes= unicellular or multicellular

• Have specialized organelles

• Linear DNA

Cell Organelles

• Nucleus• Ribosomes• Mitochondria• Chloroplasts• Endoplasmic Reticulum (ER)• Golgi Apparatus• Vesicles/Lyosome• Vacuoles

Nucleus• Largest organelle in most eukaryotic

cells• Houses genetic information (DNA)

– DNA organized into chromosomes • Number of chromosomes depends on

species– Humans= 23 pairs; Kangaroos= 6 pairs

• Directs cell activities• Nucleolus= within nucleus

– Makes ribosomes

• Surrounded by nuclear envelope– Double membrane– Contains pores

• Ribosomes, small proteins and RNA can move in/out

Ribosomes

• Makes proteins• Found free in

cytoplasm OR associated with ER

ONE STEP UP: WHY SOME

FREE AND SOME

ASSOCIATED WITH ER?

Think about this, we’ll

come back to it.

Mitochondria• Powerhouse of the cell

– Makes energy for the cell to use

• ATP (adenosine triphosphate)

• Surrounded by two membranes– Outer membrane– Inter membrane space– Inner membrane– Matrix

• Evolved from bacteria– Endosymbiotic theory

• Has its own DNA and ribosomes

Chloroplasts

• Membrane bound organelles in plant cells and some protists (algae)

• Use light energy to make glucose– From water and

carbon dioxide

• Glucose= sugar– Sugar= energy

Endoplasmic Reticulum (ER)• Smooth ER

– Synthesis• Cholesterol• Steroid

– Calcium regulation

• Rough ER– Rough because

associated with ribosomes

• Involved in protein production and export

– Lumen (inside) is contiguous with space between membranes in nucleus

ONE STEP UP: WHY ARE THERE

RIBOSOMES FLOATING IN CYTOPLASM

AND RIBOSOMES ASSOCIATED WITH

rER?

Golgi Apparatus• Looks like stack of

pancakes• Post office of the cell

– Packages and organizes synthesized proteins into vesicles

• Exocytosed• PM• Lysosome

• Cis= part closest to ER• Trans= part closest to

PM

Vesicles/Lysosome• Tiny membrane bound

balls that are used to move things – Around the cell– Out of the cell– Into the cell

• Lysosome= specialized vesicle– Stomach of the cell– Breaks down things for the

cell to use– Removes waste

Vacuole

• Usually in plant cells– One large vacuole

• Store food, water and waste

• In some animal cells– As many small

ones, not one big one

HOMEWORK

• Vocabulary words on flash cards– Memorize for quiz

• Outline Lesson 2

• Page 58 (Lesson 2 review)– Questions 1-11

• QUIZ on Lesson 1 and Lesson 2

BELL WORK CH2 L.3• Passive transport: the movement of substances through

a cell membrane without using the cell’s energy• Diffusion: the movement of substances from an area of

higher concentration to an area of lower concentration• Osmosis: the diffusion of water molecules only through a

membrane• Facilitated diffusion: the process by which molecules

pass through a cell membrane using special proteins called transport proteins

• Active transport: the movement of substances through a cell membrane using the cell’s energy

• Endocytosis: the process during which a cell takes in a substance by surrounding it with the cell membrane

• Exocytosis: the process during which the cell’s vesicles release their contents outside the cell

Lesson 3: Moving Cellular Material

• How do materials enter and leave the cell?

• How do materials get around the cell?

• How does the cell size affect the transport of materials?– Different mechanisms for different sizes?

Membranes

• Act as barriers

• Semi-permeable– Some things can pass through membrane

with no help– Some things have to be transported across

Passive transport• Passive= no energy required

– Depends on concentration difference on either side of membrane

– Things diffuse FROM high concentration TO low concentration until equal concentration on both sides (equilibrium)

• Move things down concentration gradient• Favorable reaction= no energy required

• Small things like oxygen and carbon can pass through the membrane

• Kinds of passive diffusion:– Simple & Facilitated

Simple Diffusion• No energy

required and no help required– Can move

across membrane by itself

• Osmosis= special kind of diffusion– This is when

WATER is moving across the membrane

ONE STEP UP: WHAT WILL

HAPPEN IF YOU PUT A

FRESH WATER FISH IN A

SALT WATER TANK?

Facilitated diffusion

• Still passive diffusion= no energy required

• Facilitated= needs help– Too large to move across

membrane solo– Need help of a transport protein

• Found in PM

– Channel Protein or Carrier protein

• Channel protein– Form pores for the protein to

travel through– Ions go through these

• Carrier protein– Carries protein across membrane

(conformational change)– Sugar molecules do this

Active transport• Active= needs energy (ATP)

– Going UP/AGAINST concentration gradient– Moving from low to high concentration– Not favorable

Diffusion vs Active transport

Endocytosis• Cell takes IN a substance by surrounding it with cell membrane– Too big to pass

through membrane via transporter

ONE STEP UP: WHAT DO YOU THINK HAPPNES

TO THE VESICLE ONCE IT IS ENDOCYTOSED?

Exocytosis• Substances leave the cell• Vesicles containing particles within the cell fuse

with the PM and dump the contents of the vesicle outside the cell

ONE STEP UP: WHAT

KINDS OF THINGS DO

YOU THINK GET

EXOCYTOSED?

Cell Size and Transport

• Area of cell membrane is large– Area of membrane= cell surface area

• As the cell grows, the volume grows and the surface area grows– Volume grows faster than area

• Surface area has to be bigger than volume

– Cell can’t get too big• Limited by surface area• Big cell= lots of movement in the cell

ONE STEP UP: HOW DO YOU THINK THINGS

MOVE WITHIN THE CELL?

MiniLab p.63

• Work in pairs.

• Discuss with your partner as you go through questions.

• Should have 3-column table and answered questions 1-4

HOMEWORK

• Vocabulary words on flash cards– Memorize for quiz

• Outline Lesson 3

• Page 66 (Lesson 3 review)– Questions 1-11

BELL WORK CH2 L.4• Cellular respiration: a series of chemical

reactions that convert the energy in food molecules into a usable form of energy called ATP

• Glycolysis: a process by which glucose, a sugar, is broken down into smaller molecules

• Fermentation: a reaction that eukaryotic and prokaryotic cells can use to obtain energy from food when oxygen levels are low

• Photosynthesis: a series of chemical reactions that convert light energy, water, and carbon dioxide into the food energy molecule glucose and give off oxygen

Lesson 4: Cells and Energy

• How do cells make energy?

• How do cells make food molecules?

• How does the air you breathe in differ from the air you breathe out?

Cellular Respiration

• Series of chemical reactions to convert the energy in food molecules into a usable form of energy called ATP

• First part takes place in cytoplasm, second part takes place in the mitochondria.

Glycolysis

• In the cytoplasm• Glucose is broken down

into smaller molecules– Produces some ATP but not

main source of ATP• Has to use some ATP also• Uses 2 and makes 4 so NET 2

ATP

– No oxygen is used in this step

• Anaerobic

Reactions in Mitochondria• Second part of cellular respiration

– This is where the majority of the energy is made• Remember: mitochondria is the powerhouse of the cell

• End products of glycolysis are used in the mitochondria to make lots of ATP

• Uses oxygen here• Waste products: carbon dioxide and water

Fermentation

• Reaction that eukaryotes and prokaryotes can use to obtain energy from food when oxygen levels are low– No oxygen= less ATP made than cellular

respiration

• Occurs in the cytoplasm• Two kinds

– Lactic acid fermentation– Alcohol fermentation

Lactic acid fermentation

• Glucose is used to make ATP but no oxygen so can’t do cellular respiration– Waste product= lactic

acid

• Muscle cells use this during exercise

• Bacteria use this to help make yogurt and cheese

Alcohol fermentation

• Glucose used to make ATP but no oxygen so can’t do cellular respiration– Waste product= ethanol and carbon dioxide

Photosynthesis• Plants obtain energy from

light• Series of chemical

reactions that converts light energy, water and carbon dioxide into food-energy (glucose) and gives off oxygen

• Chlorophyll (in chloroplasts) absorb light energy= absorbs all colors except green

ONE STEP UP: WHY IS IT

SO IMPORTANT TO KEEP

TREES ALIVE AND KEEP

PLANTING THEM?

HOMEWORK• Vocabulary words on flash cards

– Memorize for test

• Outline Lesson 4

• Page 73 (Lesson 4 review)– Questions 1-11

• Quiz next class

BELL WORK CH2- review

• Write four possible exam questions – Two from Chapter 1– Two from Chapter 2

• Also include complete answer

• Fair questions may be included in exam

Lab p.74

• Work in pairs

• One person is full light, one person is less light

• Combine data at the end of experiment

Review/Organize

• Vocabulary

• Outlines

• Key topics

• Review Questions

• Science notebook- CH2

HOMEWORK

• Test for CH1 & CH2 – Study guide:

• Vocabulary flash cards• Lesson outlines• Lesson review questions• Notes from class

• EXTRA CREDIT (must do all of it): – (+5 points on exam)– Page 78-79 Chapter 2 Review– Page 80-81 Standardized Test Practice