Cell Structure & Function!

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Cell Structure & Function!

Chapter 3!

“The most exciting phrase to hear

in science, the one that heralds

new discoveries, is not 'Eureka!'

but 'That's funny….’ ”!

-- Isaac Asimov

Animal Cell

Plant Cell

Cell Structure/Function

Cell membrane/wall - protective, permeable layer

around outer boundary of cell provides structure

Bacteria:

Cell wall made of peptidoglycan

Plants:

Cell wall made of cellulose

Cell Structure/Function

Cytoplasm – consists of all cellular structure inside

the membrane except the nucleus 2 Components: cytosol and organelles

Cytosol –

intracellular fluid

site of many chemical reactions needed for cell existence

water, ions, glucose, amino acids, fatty acids, proteins, lipids, ATP, and waste products

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Cell Structure/Function

Organelles – specialized structures within cell perform specific functions in cell growth, maintenance, and reproduction

Numbers and types of organelles vary from cell to cell depending on cell’s function

Each has own set of enzymes for specific reactions

Cell Structure/Function

Enzymes – proteins that speed up (catalyze)

chemical reactions

provide alternate pathway that requires less energy to start reactions

enzymes remain

unchanged after

reactions

Cell Structure/Function

Nucleus – stores DNA

Note: all cells have same DNA

different genes turned ‘on’ in different cells

‘Head Office’!

Cell Structure/Function

Chromatin – a combination of DNA and associated

proteins

Chromosomes – long threadlike structures

a single piece of DNA containing many genes 46 in humans

Within the nucleus:

Genes – subunits of DNA that control particular

hereditary characteristics

Cell Structure/Function

Nucleoplasm – semi-fluid surrounding chromosomes Nucleolus – location where ribosomal RNA is

produced

Nuclear envelope – membrane surrounding

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Cell Structure/Function

Ribosomes – responsible for synthesis of proteins

Found: individually in cytoplasm in groups (polyribosomes)

attached to endoplasmic reticulum

‘Production’!

ribosomes!

Cell Structure/Function

Rough Endoplasmic Reticulum –

attached to nuclear envelope

responsible for folding, processing, and transport of proteins

‘Packaging’!

Cell Structure/Function

Smooth Endoplasmic Reticulum –

attached to rough endoplasmic reticulum

synthesizes phospholipids in membranes forms vesicles to transport products to Golgi apparatus

‘Shipping’!

Cell Structure/Function

Vesicles –

membranous sac

stores and transports cell products

‘Interoffice Mail’!

Cell Structure/Function

Vacuoles (vesicle) --

large membranous sac - most prominent in plants stores & transports cell products

storage of substances – water, sugars, salts,

pigments (flower color), toxic substances (self-defense)

Cell Structure/Function

Peroxisomes (vesicle) –

contains enzymes that oxidize

(remove H atoms from) organic substances examples: amino acids, fatty acids, alcohol byproduct: hydrogen peroxide (H2O2)

enzyme catalase decomposes H2O2 self-replicating

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Cell Structure/Function

Lysosomes (vesicle) –

membrane-enclosed vesicles formed in the Golgi

complex

~60 different kinds of digestive & hydrolytic enzymes

‘Sanitation Workers’!

Most numerous in

disease-fighting cells, such as

white blood cells

Enzymes are created in the RER

Breaks down worn cell parts and substances entering cell

Cell Structure/Function

Proteasomes –

Barrel-shaped structures that handle destruction of

unneeded, damaged, or faulty proteins

Enzymes cut proteins

into amino acids, which are recycled into new proteins Cell contains 1000s of proteasomes

Cell Structure/Function

Plastids (vesicle)– manufacture & storage of chemical

compounds in plant & algae cells

Etioplasts – chloroplasts that have not

been exposed to light

Chloroplasts – photosynthesis Chromoplasts – pigment synthesis &

storage

Leucoplasts – synthesis of resins Amyloplasts: starch storage &

detecting gravity!

Elaioplasts: fat storage

Proteinoplasts: storing, modifying

proteins

Cell Structure/Function

Golgi apparatus – a collection of folded curved sacs collects, sorts, packages and distributes goods created by the

ribosomes and ER to rest of cell

‘Post Office’!

Cell Structure/Function

Chloroplasts –

use solar energy to create organic molecules

(in plant cells) ~50 in each cell

‘Power Generator – Plants & algae’!

food producers of cell

create sugars from CO2 & H2O

need light energy byproduct is oxygen

Cell Structure/Function

Mitochondria –

responsible for generating ATP (energy)

100s to 1000s in each cell

self-replicate if increased energy demands

‘Power Generator – Plant & Animal’!

contain their own DNA – 37 genes only inherited from your mother!

Sugar combines with oxygen on surface

of cristae (inner membrane) to form

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Cell Structure/Function

Cytoskeleton –

Network of protein filaments throughout the cytosol

Provide strength and shape for the cells 3 different sizes (diameters)

Microfilaments – found at edges of cell

Composed of protein actin

Generate movement and provide mechanical support Intermediate filaments – exceptionally strong

Found in parts of cell that experience mechanical stress

Stabilize position of organelles within cell

Help attach cells to one another

Cell Structure/Function

Microtubules – created in centrosome

Long hollow tubes

Composed of protein tubulin Help determine cell shape

Cell Structure/Function

Centrosome –

pair of centrioles & pericentriolar material Located near nucleus

Replicate in cell division so new cells can also divide Centrioles --Two

cylindrical structures 9 clusters of 3

microtubules arranged in circular pattern

Pericentriolar material – helps in cell division and

in microtubule formation

Cell Structure/Function

Cilia –

Numerous short hairlike projections that extend from

surface of cell

Made of microtubules arranged in specific pattern

Flagella – similar to cilia

except larger

Propels entire cell

Example: sperm cell tail Movement of cilia creates steady flow of fluid across exterior of cell

Chapter Objectives

Label the structures within the eukaryotic cell

Describe the functions of cell structures

Compare and contrast prokaryotic and eukaryotic cells

– give examples of each

Know the key differences between plant and animal cells

Vocabulary

Be able to define the following; describe the functions of bolded items:

eukaryotic endomembrane system: cytoskeleton: prokaryotic rough endoplasmic reticulum actin (micro) filaments plasmid smooth endoplasmic reticulum intermediate- cytoplasm vesicle(s) filaments cytosol vacuole(s) microtubules nucleus Golgi apparatus cilia Nuclear envelope lysosome flagella nucleolus proteasomes centrioles chromatin energy related structures:

ribosome mitochondria peroxisome chloroplast