Parts of the cell | Ch. 6

Cell

All living things are made up of one or more cells

• smallest unit of life

• New cells come from existing cells

• Cell - tissue - organ - organ system

Prokaryotes

Single celled organisms

Has a “like nucleus” not real though

Includes:

• Nucleotide

• Cell wall

• Capsule

• Flagellum!!

Eukaryotes

Makes up plants, animals, fungi, etc

• The more complex/ has more organelles cell

• Has a true nucleus

Includes:

• nuclear membrane

• Nucleus

• Nucleolus

• Cytoplasmic membrane

• Cytoplasm

• Mitochondrion

• Golgi

• Chloroplast

Animal cells

Eukaryotic cell

Added organelles:

• includes centrioles

• Lysosomes

• Centrosomes

Plant cell

Eukaryotic cell

Added organelles:

• cHloroplasts

• Cell wall

• plasmodesmata

Plasma membrane

The outside barrier of the cell!

• made up of phospholipid bilayer with embedded proteins and cholesterol!

• Regulates what comes in and goes out (semi-permeable)

Cytosol

Term referred as the fluid in the cell (the empty space)

Made of water

Site of many chemical reactions

Cytoplasm

The term used to describe all content within cell membrane

Nucleus

Site of the dna replication and mRNA synthesis

• chromosomes in nucleus!

• Pores to let in/out molecules

Includes:

• nuclear envelope

• Nucleolus

• Ribosomes

Nuclear envelope

Surrounded by 2 phospholipid bilayers

Nucleolus

Production of ribosomes!

Ribosomes

Site of protein synthesis(making of proteins), made up of rRNA and proteins!

2 types-

• bound ribosomes

• Free ribosomes

Free ribosomes

Produce proteins mostly used in cell, they are free to roam around

Bound ribosomes

Produce proteins exported from cell

• bound to the rough ER!

Endomembrane system

• The UPS of the cell!

• Resulting proteins shipped to various locations

Group of organelles involved in protein/lipid synthesis/modification, important for enzymes, structures, cell communication, and hormones, energy, and forming cell membrane

Includes: nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vesicles

Endoplasmic reticulum (ER)

Network of flattened tubules

Major role in protein and lipid synthesis

• composed of rough and smooth ER

Rough ER

• has Bound ribosomes

Functions:

• Protein synthesis: Polypeptides produced by bound molecules enter RER (rough endo reticulum)

• Protein modification: A structurally modified polypeptide becomes a protein (and a secretory protein is called glycoprotein)

• Transportation: Proteins produced in RER transported to Golgi apparatus in vesicles

Smooth ER

Has no ribosomes but produces various of lipids (fatty acids and steroids)

Those lipids are then transported to the Golgi appartus

Functions:

• Detoxification: drugs and alcohol

• Storage for calcium ions: cell signaling

Golgi apparatus

FedEx of the cell!

flattened stacks and has a directionality (cis and trans)

• cis: closest to ER

• Trans: closest to plasma membrane

Materials are transported between stacks via vesicles

3 primary functions:

• Processing: modification of proteins and lipids

• Proteins and lipids sorting: determines which stay/go

• Secretion: packages them so they can be released outside cell

Mitochondria

Produce ATP!! (Powerhouse of the cell)

Functions:

• cell respiration

• 2 phospholipids membranes! (Outer/inner)

endosymbiosis Theory

• mitochondria and chloroplasts were once independent prokaryotic microbes

• Large cell engulfed these smaller bacteria

Chloroplasts

Plants only!

• photosynthesis role

• 2 phospholipid membranes

Lysosomes (animals only)

Digestive vesicles

• enzymes that degrade macromolecules

• Extremely acidic

Functions:

• fights pathogens: phagocytosis

• Autophagy: breakdown/recycle of organelles

Failure of this organelle is: Tay-Sachs

Peroxisomes

Function in detoxification:

Removes hydrogens from toxic compounds and turns into water

Very abundant in liver/kidneys!

• helps breakdown of very long fatty acids!

Cytoskeleton

• in Eukaryotes!

Network of fibers used for structural support, organization, anchoring, and movement

• 3 types:

• Microtubules

• Intermediate filaments

• Microfilament

Microtubles

Largest, hollow tube, made of tubulin

• functions in shape, cell division, and motility

Intermediate filaments

Coiled keratin protein strands, anchoring!

• functions in cell anchoring

• Not found in cell plants

Microfilament

The thinnest

• two strands of actin (Protein)

• Functions in muscles contraction and cellular movement!

Cell junctions

Specialized structures that connect neighboring cells

• hold tissues together

• Communication between cells

Animals cells junction

Tight junctions!

• plasma membrane of cells held tightly together

Includes:

• Desmosomes: anchors cells together

• Gap junctions: cytoplasmic channels between cells

Plant cells

• Plasmodesmata: cytoplasmic channels between cells