The cell theory and homeostasis

The cell theory

• With the invention of the microscope and the help of many different scientists, a very important questions was answered in the 1850’s:

WHERE DO CELLS COME FROM?

The cell theory

• There are 3 concepts to the cell theory:– Every living thing is made up of one or more cells– Cells are the smallest unit of life– All cells come from preexisting cells

Every living thing is made up of one or more cells

• There are two types of cells:– Prokaryotic

• First cell to evolve• No nucleus• DNA (genetic information) contained in the cytoplasm of the cell• Growth is usually through the expansion of the cell• Examples: Archaea and Bacteria

– Eukaryotic• Evolved from prokaryotes• Have a nucleus• DNA contained within the membrane-bound nucleus• Growth is usually through an increase in number of cells• Examples: Animals, Protists, Fungi, Plants

Every living things is made up of one or more cells

• Prokaryotes are unicellular. This means that all functions of life happen within that one cell

• Eukaryotes are unicellular (protists) and multicellular. If the organism is multicellular, different cells have different jobs and they all work together to perform the functions of life

• Both unicellular and multicellular organisms follow the 6 characteristics of life

The functions/characteristics of life

• Organization– Living things have specialized structures with specialized functions

• Growth and Development– When organisms grow, they increase in size (unicellular) or number of

cells (multicellular). Changes that occur in an organism during its lifetime are called development.

• Reproduction– The process by which one organism makes one or more new organisms– Not all organisms of a species must reproduce in order for the species

to survive (only some need to)

The functions/characteristics of life

• Response to Stimuli– When an organism responds to changes in its internal or external

environment– Internal stimuli are responses to needs within the body (hunger, aches, etc.)– External stimuli are responses to needs outside of the body (fear, sunlight,

etc.)

• Homeostasis– An organism’s ability to maintain steady internal conditions when outside

conditions change

• Use of Energy– Cells continuously use energy to transport substances, make new cells, and

perform chemical reactions. – People use energy for everyday tasks like sleeping, eating, etc.

• Things that have all the characteristics of life are called organisms

The cell organelles

organelles

• The size and shape of a cell relates to its job or function

• A cell is made of different structures that perform different functions and keep a cell alive. These structures also have unique functions

• Organelles are tiny membrane-bound structures that perform special functions in the cell

Cell wall

• Only found in plant, fungi, bacteria, and some protist cells

• Rigid and strong to hold the cell’s shape

• Provides support and protection for the cell

Cell/plasma membrane

• Found in all cell types– In plant cells, it lies

beneath the cell wall– In animal cells, it is

the outer boundary

• Provides the cell with– Protection– Control of the

movement of materials in and out of the cell

– Support– Maintains the internal

conditions of the cell

nucleus

• Found in both plant and animal cells

• Consists of the nuclear membrane, nucleoplasm, and nucleolus

• Controls cell activities and contains DNA

• The nucleolus makes ribosomes

Cytoplasm and the Cytoskeleton

• Found in both plant and animal cells

• Cytoplasm is thick, jelly-like substance located beneath the cell membrane that supports and protects the cell’s organelles

• The cytoskeleton gives the cell its shape and helps it move

Golgi apparatus

• Found in both plant and animal cells

• Looks like a flattened stack of pancakes

• Processes and packages molecules made by the cell for transport around the cell or out of the cell in vesicles

ribosomes

• Found in both plant and animal cells

• Can be found attached the endoplasmic reticulum or floating free in the cytoplasm

• Produces proteins

• The smallest organelles

Endoplasmic reticulum• Found in both plant

and animal cells• Network of tubes

that transports materials throughout the cell

• Two types:– Smooth ER (no

ribosomes)• Makes lipids

and removes harmful substances

– Rough ER (has ribosomes)• Site of protein

production

mitochondria

• Found in both plant and animal cells

• Breaks down sugar molecules to release energy for the cell to use

• Known as the “powerhouse” of the cell

• Has inner folds called cristae to increase its surface area

vacuoles

• Found in both plant and animal cells– In plant cells, there

are very few of them but they are very large

– In animal cells, they have very many little ones

• They are fluid-filled sacs that store food, water, and waste

lysosomes

• Found only in animal cells

• Break down larger food molecules into small food molecules

• Digest old cell parts

chloroplasts

• Found only in plant cells

• Green in color because of chlorophyll

• Use energy from the sun to make food for the plant

Levels of life’s organization

It all adds up

• All matter is composed of atoms and atoms combine to form molecules

• All living organisms are made of cells (which are composed of molecules)….but how do those cells make organisms?

• Cells build together to make tissues– Tissues build together to make organs

• Organs build together to make organ systems– Organ systems build together to make organisms

Cells build together to make tissues

• The process by which cells become different types of cells is called cell differentiation

• In multicellular organisms, similar types of cells are organized together into groups.

• Tissues are groups of similar types of cells that work together to carry out a specific task

Types of tissues• Humans have four types of tissues:– Muscle – causes movement– Connective – provides structure and support– Nervous – carries messages to and from the brain– Epithelial – forms the protective outer layer of skin

and lining of major organs• Plants have three types of tissues:– Dermal – provides protection and prevents water loss– Vascular – transports water and nutrients– Ground – provides storage and support; where

photosynthesis takes place

Tissues build together to make organs

• Complex jobs in the body require the use of more than one type of tissue

• Organs are groups of tissues working together to perform a particular job

• Organs usually involve all four types of tissues in humans and all three types of tissues in plants

Organs build together to make organ systems

• Organs do not usually function alone• Organ systems are groups of different organs

that work together to complete a series of tasks

• Humans have 11 different organ systems in their body and plants have 2

Organ systems build together to make organisms

• Multicellular organisms usually have many different organ systems that work together to perform daily life tasks that are needed for the survival of that organism

Human Body Systems

System Function Diagram Major Organs

Interactions with Other Systems

Digestive

1. take in food (ingestion)

2. digest food into smaller molecules

and absorb nutrients

3. Remove undigestable food from body (feces)

Mouth, esophagus,

stomach, Sm.Intestine, Lg.

intestine,rectum, anus

Salivary glands

1. w/circulatory – absorb & deliver the digestednutrients to the cells

2. w/muscular – control the contractions of many of the

digestive organs to pass food along

3.w/nervous –hypothalamus maintains homeostasis by

triggering appetite (stomach growling), digest.

RespiratoryTakes in oxygen

and removes carbon

dioxide and water

NoseTracheaBronchi

BronchiolesAlveolilungs

1. w/circulatory – takesin O2 for delivery to cells

and removes CO2 brought from cells

2. w/excretory – removesexcretory waste

3. w/nervous – controlsbreathing

4. w/muscular – diaphragm controls Breathing

System Function Diagram Major Organs

Interactions with Other Systems

Circulatory Transport

materials to and from cells

HeartVeins

ArteriesCapillariesRed blood

cells

1. w/respiratory – deliver O2 from lungs to cells and drop off

CO2 from cells to lungs2. w/digestive – absorb anddeliver digested nutrients to

cells3. w/excretory – kidneys filter cellular waste out of blood for

removal4. w/lymphatic – both transport

things to and from cells5. w/immune – transports

WBCs throughout body to fight disease

6. w/nervous – brain controlsheartbeat

7. w/endocrine – trans. Hormones

Reproductive

Allows organisms to

reproduce which

prevents their species from

becoming extinct.

Ovaries*produce

eggs

Testes*produce

sperm

1. w/endocrine – controlsproduction of sex cells2. w/muscular – uteruscontracts to give birth –controlled by hormones

System Function Diagram Major Organs Interactions with Other Systems

Excretory

1. removes waste

products fromcellular

metabolism (urea,

water, CO2)2. filters blood

KidneysUretersBladderUrethra

1. w/circulatory – filters waste out of blood

2. w/lungs –removes excretory waste

3. w/integumentary – removes excretory waste

ImmuneFights off foreign

invaders in thebody

White BloodCells

*T cells*B cells

-produceantibodies

*MacrophagesSkin

1. w/circulatory –transports WBCs to

fight invaders2. w/lymphatic – has lots

of WBCs to fightinvaders, spleen filtersbacteria/viruses out of

blood3. w/skeletal – WBCs

made in bone marrow4. w/integumentary –

prevents invaders fromgetting in

Nervous

1. gathers andinterprets

information2. responds to

information3. helps maintain

homeostasis

BrainSpinal cord

NervesNerve cells =

neuronshypothalamus

Controls all othersystems

Hypothalamus – maintains

homeostasis by workingwith all systems

System Function Diagram Major Organs Interactions with Other Systems

Muscular Allows for

movement bycontracting

Cardiac muscleSmooth muscleSkeletal muscle

tendons

1. w/skeletal – allowmovement

2. w/digestive – alloworgans to contract to

push food through3. w/respiratory –

diaphragm controlsbreathing

4. w/circulatory – controls pumping of

blood (heart)5. w/nervous –

controls all muscle contractions

Skeletal

1. protects organs2. provides shape,

support3. stores materials

(fats, minerals)4. produces blood

cells5. Allows

movement

BonesCartilageligaments

1. w/muscular – allowmovement

2. w/circulatory –produce blood cells

3. w/immune – produce white blood

cells4. w/circulatory and

respiratory – protectsit’s organs