Biology 11E. McIntyre

Cytoplasm (cytosol): a cell's inner space

Cytoskeletoncytosol

Cytosol: large fluid-filled space (mostly water + proteins that control most of the cell metabolisms): glycolysis, transcription factors, intracellular receptors etc.

Plasma membrane

Organelles

• Nucleus• Protein production machine: the ribosomes• Mitochondria and Chloroplasts• Endoplasmic Reticulum and the Golgi

apparatus• Lysosomes and Peroxisomes• Adapted and/or specialized for carrying out

one or more vital functions

Reminder! Membrane-bound organelles are only found in eukaryotes.

Nucleus: a cell's centerFunction of the nucleus:• Stores the chromosomes

(genetic material) Note: Two kinds of genetic material:– deoxyribonucleic acid

(DNA)– ribonucleic acid (RNA)

• Keeps the DNA molecules of separated from metabolic machinery of cytoplasm.

• Makes it easier to organize DNA and to copy it before parent cells divide into daughter cells

• DNA replication and synthesis of messenger RNA (mRNA)

...Nucleus: a cell's center

Nucleolus

• Dense mass of material in nucleus

• Cluster of DNA and proteins

• Subunits must pass through nuclear pores to reach cytoplasm

• production of ribosomes in nucleolus

• One continuous membrane which spans the ER’s membrane as well. (lipid bilayers)

• Pores span bilayer and controls what enters/leaves nucleus.

Nuclear Membrane (Envelope)

Chromatin

• Cell’s collection of DNA and associated proteins• A chromosome is one DNA molecule and its

associated proteins• Appearance changes as cell divides

FUNCTION:

• assembles proteins (non cytosolic & cytosolic proteins)

• some are free in cytoplasm (cytoplasmic ribosomes), others are attached to the ER (ER ribosomes)

Ribosomes

STRUCTURE

• ER is a continuation of the outer nuclear membrane.

• Two types: Smooth and Rough. (Rough ER has ribosomes on it)

• Network of membrane that connects nuclear envelope to the cell membrane

Endoplasmic Reticulum (ER)

…Endoplasmic Reticulum (ER)

FUNCTION:

• Smooth ER (no ribrosomes): responsible for lipid and membrane protein modifications)

• Rough ER (has ribosomes on it) responsible for the synthesis of other proteins). The ribosomes assemble the proteins within the rough ER. Once assembled, the proteins pinch off the ER and are released in a vesicle.

Endoplasmic Reticulum (ER)

…Endoplasmic Reticulum (ER)

FUNCTION:

• processes, packages, and, secretes cell products (lipids & proteins)

• Put finishing touches on proteins and lipids that arrive from ER

• Package finished material for shipment to final destinations. (Exocytosis)

• Material arrives and leaves in vesicles

Golgi Body (Golgi Apparatus)

…Golgi Body (Golgi Apparatus)

STRUCTURE

• Double membrane. Inner membrane is folded for greater surface area. Folds are called cristae.

• Interior is called the matrix.

• Contain their own genome (distinct from nuclear genome)

• Self-replicating

FUNCTION

• ‘burns’ food, i.e. glucose to release energy. Energy is used to make ATP. ATP is a high-energy molecule that can be directly used by the cell.

Mitochondria

The “powerhouse” of the cell

…Mitochondria

STRUCTURE• Formed by Golgi bodies• Bound by a single membrane

FUNCTIONS• Digests the food particles inside the cell with help of enzymes. These enzymes

work at low pH.• Involved in autolysis (suicide of cell)• Digest foreign bacteria that invade a cell• Recycling of membrane components• Repair damage to plasma membrane

Lysosomes

• Made by Golgi

• Surrounded by a single bilipid membrane

• Detoxification of poisonous substances

• Many in the liver/ brain

lysosome

Peroxisomes

FUNCTION:

• maintains the shape of a plant cell

• found in plants, some fungi, some protists

• In plants, cell walls are made of a polysaccharide called cellulose.

• Structural component that wraps around the plasma membrane

Cell Wall

…Cell Wall

FUNCTION:

• Photosynthesis: converts sunlight, carbon dioxide, and water into sugar (makes food for plants)

Chloroplasts

• A large membrane bound sac

FUNCTION:• storage area for proteins and

water• Maintain structure in plant cells by means of turgor pressure

Vacuole

• very complex and dynamic cell component!

• organizes and maintains the cell's shape (e.g. epithelial cells of the gut)

• Allows organelles to remain in place or to move throughout cell

• helps during the uptake of external material (endocytosis)

• involvement in cell movement

• growth

Cytoskeleton: a cell's scaffold

microtubules microfilamentsintermediate filaments

tubulin actin keratin family

All help maintain cell shape

Cilia, flagellaChromosome movementOrganelle movement

Cytoplasmic streamingPseudopodiaCell division

Nuclear laminaAnchorage of nucleus and some other organelles

...Cytoskeleton

...Cytoskeleton

...Cytoskeleton

Molecular motors

...Cytoskeleton

Macrophage attacks bacteriaMicrofilaments (actin) allow formation of pseudopods

...Cytoskeleton

Striated Muscle

...Cytoskeleton

Centrosome: Made up of centriole pairs

...Cytoskeleton

Bibliography• http://users.ipfw.edu/mustafaa/PQ_B100-02-ppt-Chapter4-Cell%20Structures%20and%20Functions.ppt

• http://images.google.ca/imgres?imgurl=http://biology.dbs.umt.edu/biol101/labs/lab_6_images/sect05and02/cheek%2520cell%25201000x.jpg&imgrefurl=http://biology.dbs.umt.edu/biol101/labs/lab_6_images/sect05and02/section_2and5_cellimages.htm&h=768&w=1024&sz=316&tbnid=OxmCr18W6AQJ:&tbnh=112&tbnw=149&start=1&prev=/images%3Fq%3Dcheek%2Bcell%26hl%3Den%26lr%3D

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• file:///C:/WINDOWS/Temporary%20Internet%20Files/Content.IE5/UPK3G94Z/266,12,Diffusion

• http://bioweb.wku.edu/courses/biol22000/11Organelles/images/F05-43A.JPG

• http://cellbio.utmb.edu/cellbio/nucleus.html

• http://www.cellsalive.com/cells/er.htm

• cellbio.utmb.edu/cellbio/ribosome.htm

• http://cellbio.utmb.edu/cellbio/golgi.htm