Cell Structure and Function

CELL STRUCTURE AND FUNCTION

Organelles

•Very small (Microscopic)•Perform various functions for a cell•Found in the cytoplasm•May or may not be membrane-bound

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ANIMAL CELL ORGANELLES3

NucleolusNucleus

Nuclear envelope

Ribosome (attached)Ribosome (free)

Cell Membrane

Rough endoplasmic reticulum

Golgi apparatus

Mitochondrion

Smooth endoplasmicreticulum

Centrioles

Plant Cell Organelles4

Cell Structure and Function Chart

Organelle Structure Function

• Cell wall• Cytoplasm• Nucleus• Nuclear membrane• Nucleolus• Cytoskeleton• Centrioles• Mitochondria

• Rough endoplasmic reticulum• Smooth endoplasmic reticulum• Ribosome• Golgi bodies• Lysosome• Cilia• Flagella• Vacuole• Chloroplast

Cytoplasm of a Cell 6

• Jelly-like substance enclosed by cell membrane

• Provides a medium for chemical reactions to take place

cytoplasm

The Control Organelle - Nucleus7

• Controls the normal activities of the cell

• Contains the DNA in chromosomes

• Surrounded by a nuclear membrane with pores

• Usually the largest organelle

Nuclear Membrane

• Double membrane surrounding nucleus

• Also called nuclear envelope• Contains nuclear pores for materials to enter & leave nucleus

• Connected to the rough ER

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Nuclear pores

Inside the Nucleus -9

The genetic material (DNA) is found

Nucleolus

• Inside nucleus•Makes ribosomes that make proteins

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Cytoskeleton• Helps cell maintain cell shape

• Also help move organelles around

• Made of proteins

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Cytoskeleton

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MICROTUBULES

MICROFILAMENTS

Mitochondrion(plural = mitochondria)

• “Powerhouse” of the cell• Generate cellular energy (ATP)

• Both plants & animal cells have mitochondria

• Site of CELLULAR RESPIRATION (burning glucose)

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MITOCHONDRIASurrounded by a DOUBLE membrane

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Folded inner membrane called CRISTAE (increases surface areafor more chemical Reactions)

Has its own DNA

Interior called MATRIX

Interesting Fact ---• Mitochondria comes from cytoplasm in the EGG cell during fertilization

Therefore …• You inherit your mitochondria from your mother!

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Endoplasmic Reticulum - ER• Network of membranes• Connects to nuclear envelope & cell membrane• Functions in Synthesis of cell products & Transport

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Two kinds of ER ---ROUGH & SMOOTH

Rough Endoplasmic Reticulum (Rough ER)

• Has ribosomes on its surface

• Makes membrane proteins and proteins for EXPORT out of cell

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Smooth Endoplasmic Reticulum

• Smooth ER lacks ribosomes on its surface

• Is attached to the ends of rough ER

• Makes cell products that are USED INSIDE the cell (ex: lipids) and helps destroy toxic substances

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Endomembrane System19

Includes nuclear membrane connected to ER connected to cell membrane (transport)

Ribosomes• Made of PROTEINS and rRNA• “Protein factories” for cell• Join amino acids to make proteins• Process called protein synthesis

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Ribosomes

Can be attached to Rough ER

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OR

Be free (unattached) in the cytoplasm

Golgi Bodies• Stacks of flattened sacs• Receive proteins made by ER

• Package proteins and ship them to other parts of the cell OR outside the cell

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Transport vesicle

CIS

TRANS

Lysosomes• Contain digestive enzymes

• Break down food, bacteria, and worn out cell parts for cells

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Cilia & Flagella

• Both function in movement

• Cilia are shorter and more numerous on cells

• Flagella are longer and fewer (usually 1-3) on cells

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Vacuoles• Fluid filled sacks for storage

• Small or absent in animal cells

• Plant cells have a large Central Vacuole

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Centrioles• Found only in animal cells• Paired structures near

nucleus• Appear during cell

division • Help to pull chromosome

pairs apart to opposite ends of the cell

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Chloroplasts• Found only in plant cells• Use energy from sunlight to make own food (glucose)

• Energy from sun stored in the Chemical Bonds of Sugars

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Chloroplasts• Surrounded by DOUBLE membrane

• Outer membrane smooth• Inner membrane modified into sacs called Thylakoids

• Thylakoids in stacks called Grana & interconnected

• Stroma – gel like material surrounding thylakoids

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Cell Wall29

• Nonliving layer• Found in plant cells• Supports and protects

cell• Outside of cell

membrane

Cell wall

Plant vs. Animal Cell

Cell wallChloroplast

Large, central vacuoleSometimes lysosomes

CentriolesMany smaller vacuoles

All have lysosomesCytoskeleton

Plant Animal

CytoplasmNucleusNuclear

membraneNucleolus

MitochondriaER

RibosomeGolgiCilia

FlagellaVacuole

Prokaryotic and Eukaryotic Cells• Prokaryotes

• Bacterial cells• Smaller• More primitive structures

• No nucleus or membrane-bound organelles• Usually unicellular organisms

• Eukaryotes• Plant and animal cells• Have a true nucleus and membrane-bound organelles

Characteristic Prokaryotes Eukaryotes

Size of cell Typically 0.2-2.0 m m in diameter Typically 10-100 m m in diameter

Nucleus No nuclear membrane or nucleoli True nucleus, consisting of nuclear membrane & nucleoli

Membrane-enclosed organelles Absent Present; examples include lysosomes, Golgi complex, endoplasmic reticulum, mitochondria & chloroplasts

Flagella Consist of two protein building blocks Complex; consist of multiple microtubules

Cell wall Usually present Present in plant cells

Plasma membrane Simple cell membrane Present

Cytoplasm Present Present

Ribosomes Smaller size Larger size

Chromosome (DNA) arrangement Single circular chromosome Multiple linear chromosomes