Cell Structure

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Cell Structure Unit 3 Obj. 1.1.1, 1.1.2

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Unit 3 Obj. 1.1.1, 1.1.2. Cell Structure. Place an “X” next to the things you think are made of cells. ___ flowers___ hamburger___ leaf ___ skin___ DNA___ seeds ___ proteins___ calcium___ water ___ rocks___ apples___ sugar ___ milk___ sand___ blood - PowerPoint PPT Presentation

Transcript of Cell Structure

Page 1: Cell Structure

Cell StructureUnit 3Obj. 1.1.1, 1.1.2

Page 2: Cell Structure

Place an “X” next to the things you think are made of cells

___ flowers ___ hamburger ___ leaf

___ skin ___ DNA ___ seeds ___ proteins ___ calcium ___ water ___ rocks___ apples ___ sugar ___ milk ___ sand ___ blood ___ bone ___ worms ___ saliva ___ lungs ___ bacteria ___

mushroom

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What is a cell?

The smallest unit of life; the smallest thing biologists study

RECALL: Organization of Living Things:

Cell Tissue Organ Organ system Organism

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What is a cell?

Cells have smaller parts inside of them called organelles

This means “little organ.” They perform special functions for the cell to keep it (and the organism) alive.

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Cell Theory Contributed to by Theodor Schwann and

Matthias Jakob Schleiden in 1839 and Rudolf Virchow in 1858.

Three main ideas: 1. All living things are made of one or more

cells.▪ Unicellular = one-celled organism▪ Multicellular = organism made from many cells

2. Cells are the basic unit of structure and function in all living things.

3. All new cells come from pre-existing cells.

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Types of cells

1. Prokaryotic (means “before nucleus”)

No nucleus, unbound DNA

No membrane-bound organelles

Small and simple; “older” type of cell

Examples: Bacteria

2. Eukaryotic (means “true nucleus”)

Has a nucleus, DNA is inside nucleus

Has organelles Larger and more

complex; “younger” type of cell

Examples: Plants and Animals

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Cell Membrane Aka “plasma membrane” Provides protection, helps cell communicate, transports

substances in and out of cell, keeps the cell together Made of a phospholipid bilayer (phosphate head,

lipid tail, two layers) The head is hydrophilic (loves water), the tails are

hydrophobic (fears water) Selectively permeable Found in all cells

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Cell Wall

Only found in plant cells Shapes and supports the cell Provides additional protection Made of cellulose = humans cannot

digest

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Chloroplast

Found only in plant cells Contains chlorophyll = pigment

that gives plants their green color Traps sunlight to make glucose

(food) Site of photosynthesis

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Vacuole

Stores water, sugar, salts, nutrients, wastes, etc.

Large and central in plant cells Small or not present in animal cells

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Cytoplasm

Jelly-like substance that helps fill up the cell and suspend organelles

Site of many metabolic reactions

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Centriole

Only found in animal cells Made of microtubules Help the cell divide

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Golgi Apparatus

Processes and packages macromolecules that are synthesized by the cell in vesicles (membrane bound packages)

Secretion Found in eukaryotes only

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Cytoskeleton

Made of protein – microtubules and microfilaments

“Framework” of cell Provides structural support

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Lysosomes

Contain digestive enzymes Digest food, worn out organelles,

viruses, etc. Can also act as a “self-destruct

button” and cause the cell to lyse itself apoptosis

The “janitor,” “hit man,” and “suicide bomber” of the cell

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Flagellum

Tail-like projection from cell Helps cell move by whipping around

in a circle similar to helicopter blade

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Cilia

Small, hair-like projections Used to help cell move and sense

environment

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Pseudopodia

“False foot” Temporary projections of eukaryotic

cells Usually found in amoeba Cells use extension and contraction

to move around

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Plasmid

DNA molecule that is separate from and can replicate independently from chromosomal DNA

Usually found in prokaryotes

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Eyespots

Photoreceptive organelle = can sense light

Usually found in unicellular photosynthetic cells, like green algae

Allows the organism to respond to light and swim towards it or away from it

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Plant cells vs. Animal cells

Plant Cells Animal CellsMembrane surrounding cytoplasm

Yes Yes

Nucleus Yes, near cell wall

Yes, near center of cell

Mitochondria Yes YesChloroplast Yes NoVacuole Yes, large and

centralSmall or absent

Cell Wall Yes NoCentrioles No YesFood storage Starch Glycogen

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To be or not to be… multicellular What are some advantages?

Differentiation More control over internal conditions Greater motility able to move around and

avoid predators and find more food Genetic diversity greater chance for

positive traits What are some disadvantages?

Harder to reproduce must find a mate first Need more resources

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Cell Specialization

When cells have different jobs or functions

Only multicellular organisms can have specialized cells

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Specialized Animal Cells

Muscle, bone, brain, nerve, skin, hair= all different cells with different functions

Muscle cells: have more mitochondria than other cells= more metabolism!

Cool fact: Muscle cells have more than one nucleus!

Red Blood Cells: lose their nucleus and are donut-shaped to carry oxygen molecules

Remember: Hemoglobin is a protein

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How do you get specialized cells? Start as a stem cell = has the

ability to become any cell in the body a “blank slate”

Gets signals (usually hormones) to become a certain cell type (this is called differentiation)

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Cell Communication - Chemical Hormones = proteins that are used by both

plant and animal cells to send messages Produced in large amounts, usually in

response to something environmental Travel slowly throughout the organism Endocrine system (thyroid, testes, ovaries,

pituitary gland, etc.) releases hormones into the blood stream

Affects only those cells with the right receptors = has effects on certain cells in the body

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Cell Communication - Electrical Neurons = cells in the

nervous system that transmit information throughout the body. Animals only!

Sends messages that can be voluntary or involuntary

Send out neurotransmitters that get passed from neuron to neuron

Neurons have two main parts: dendrite and axon