DAT BIO Cells and Organelles

What are the 4 major components of the cell membrane?

Phospholipid bilayer, membrane proteins, carbohydrates, cholesterol

Main function of the cell membrane?

Selectively permeable barrier regulating movement in and out of the cell

What are phospholipid heads and tails?

Heads = hydrophilic; tails = hydrophobic

Which part of the membrane blocks water-soluble substances?

Hydrophobic fatty acid tails

What is the fluid mosaic model?

Membrane components move freely within the membrane

“Fluid” in fluid mosaic model refers to what?

Free movement of membrane components

“Mosaic” in fluid mosaic model refers to what?

Multiple structures/components in membrane

Higher temperature has what effect on membrane fluidity?

Increases fluidity

How does cholesterol affect membrane fluidity?

Stabilizes membrane; decreases excess fluidity at high temps and prevents solidification at low temps

Saturated vs unsaturated fatty acids: which increases fluidity?

Unsaturated fatty acids increase fluidity

Why do saturated fatty acids decrease membrane fluidity?

They pack tightly together

Integral membrane proteins are located where?

Embedded in membrane

Peripheral membrane proteins are located where?

On membrane surface

What does “transmembrane protein” mean?

Protein spans entire membrane

Main functions of membrane proteins?

Transport, signaling, structural support

Main functions of membrane carbohydrates?

Cell recognition, signaling, adhesion

What are glycoproteins used for?

Cellular recognition

What is adhesion?

Proteins attaching cells to each other or anchoring cytoskeleton

What is an agonist?

Molecule that binds receptor and activates response

What is an antagonist?

Molecule that blocks receptor activation

Cholesterol is found mainly in what type of cells?

Eukaryotic cell membranes

What are the 3 major transport methods across membranes?

Simple diffusion, facilitated transport, active transport

Simple diffusion moves substances in what direction?

Down concentration gradient

Does simple diffusion require energy?

No

Examples of molecules using simple diffusion?

O₂, CO₂, H₂O, steroids

What types of molecules use facilitated transport?

Large or charged molecules

Facilitated transport requires what?

Channel proteins

Does facilitated transport require ATP?

No

Examples of facilitated transport molecules?

Glucose, Na⁺, K⁺, Cl⁻

Active transport moves molecules in what direction?

Against concentration gradient

Does active transport require energy?

Yes

What powers primary active transport?

ATP hydrolysis

Classic example of primary active transport?

Sodium-potassium pump

Function of sodium-potassium pump?

Maintains membrane potential

Secondary active transport gets energy from what?

Another molecule moving down electrochemical gradient

What is cotransport?

One molecule moving down gradient drives another against gradient

What is endocytosis?

Membrane internalizes extracellular substances

Phagocytosis means what?

Cellular eating

Pinocytosis means what?

Cellular drinking

Receptor-mediated endocytosis is initiated by what?

Ligands binding membrane receptors

What protein facilitates clathrin-mediated endocytosis?

Clathrin

What forms during clathrin-mediated endocytosis?

Coated vesicle

What is exocytosis?

Release of substances outside cell

Relationship between endocytosis and exocytosis?

Opposite processes

Organelles are found in what type of cells?

Eukaryotes

Cytosol vs cytoplasm?

Cytosol = intracellular fluid; cytoplasm = cytosol + organelles

Main function of nucleus?

Stores and protects DNA

DNA replication occurs where?

Nucleus

Transcription occurs where?

Nucleus

Translation occurs where?

Cytoplasm/ribosomes

What do prokaryotes have instead of nucleus?

Nucleoid

Nucleoplasm is what?

Cytoplasm inside nucleus

Function of nuclear pores?

Channels through nuclear envelope

Function of nucleolus?

Produces rRNA/ribosome components

Main function of ribosomes?

Protein synthesis

Are ribosomes organelles?

No

Eukaryotic ribosome size?

80S

Eukaryotic ribosomal subunits?

60S and 40S

Prokaryotic ribosome size?

70S

Prokaryotic ribosomal subunits?

50S and 30S

Free ribosomes produce proteins for where?

Inside the cell

Rough ER ribosomes produce proteins for where?

Membrane insertion or secretion

Organelles included in endomembrane system?

Nucleus, ER, Golgi, lysosomes, vacuoles, membrane

Main function of endomembrane system?

Modify/package/transport proteins and lipids

Why is rough ER “rough”?

Ribosomes attached

Main function of rough ER?

Protein synthesis/modification

Rough ER proteins are sent where?

Cell membrane or extracellular space

Rough ER consists of what structures?

Cisternae

Main functions of smooth ER?

Lipid synthesis, steroid production, detoxification

Main function of Golgi apparatus?

Modify, sort, package, export proteins

Proteins enter Golgi on which side?

Cis face

Proteins leave Golgi on which side?

Trans face

Main function of lysosomes?

Digest waste using hydrolytic enzymes

Lysosomes help facilitate what process?

Apoptosis

Lysosomes are mainly found in what cells?

Animal cells

Main functions of peroxisomes?

Fatty acid breakdown and detoxification

Peroxisomes generate what toxic molecule?

Hydrogen peroxide

What enzyme breaks down hydrogen peroxide?

Catalase

Main function of vacuoles?

Storage and transport

Plant vacuoles help maintain what?

Turgor pressure/cell rigidity

Contractile vacuoles do what?

Pump out excess water

Main function of mitochondria?

ATP production via cellular respiration

Mitochondrial inheritance is from whom?

Mother

Main function of chloroplasts?

Photosynthesis

Chloroplasts are found in what organisms?

Plants and some protists

Main function of cytoskeleton?

Structural support and movement

3 major cytoskeletal filaments?

Microfilaments, intermediate filaments, microtubules

Smallest cytoskeletal structure?

Microfilaments

Microfilaments are composed of what?

Actin

Microfilaments are important for what?

Cell movement

Cleavage furrow uses what proteins?

Actin and myosin

Cyclosis means what?

Cytoplasmic streaming

Muscle contraction depends on what proteins?

Actin and myosin

Main role of intermediate filaments?

Structural support

Keratin is what type of filament?

Intermediate filament

Largest cytoskeletal filament?

Microtubules

Microtubules are composed of what?

Tubulin

Microtubules are important for what?

Cell shape, movement, spindle fibers

What structures do microtubules form?

Centrioles, cilia, flagella

Function of flagella?

Cell movement