Cell Structure and Functions (chapter 3)

What are the 3 parts of Cell Theory?

• Organisms are composed of cells.

• Cells are the basic unit of organization.

• Cells arise from pre-existing cells

What is the basic unit of life?

The cell

What are the 4 major functions of cells?

• Metabolize and release energy

• Synthesize molecules

• Communicate

• Reproduce and pass on genetic information

What is metabolism?

The chemical processes cells use to process nutrients and obtain energy.

What does "synthesize" mean?

To build or make something.

What molecule is the main usable energy source for cells?

ATP

Where are ribosomes produced/assembled?

In the nucleolus.

What is the function of ribosomes?

Protein synthesis (making proteins).

What is the main function of the Golgi apparatus?

It modifies, sorts, packages, and ships proteins and lipids

What do lysosomes do?

They digest and recycle waste, damaged cell parts, and other materials

What are the 5 major functions of membrane proteins?

• Marker molecules

• Attachment proteins

• Transport proteins

• Receptor proteins

• Enzymes

What do marker molecules do?

Allow cells to identify/recognize one another.

What are glycoproteins?

Proteins with carbohydrates attached.

What are glycolipids?

Lipids with carbohydrates attached.

What do attachment proteins do?

Help cells attach to other cells or the extracellular matrix.

What are cadherins?

Attachment proteins that help cells attach to other cells.

What are integrins?

Attachment proteins that help cells attach to the extracellular matrix.

What are integral proteins?

Proteins embedded in the plasma membrane.

What are peripheral proteins?

Proteins attached to the surface of the membrane.

What is diffusion?

Movement of molecules from high concentration → low concentration.

Does diffusion require ATP?

No

What is osmosis?

The movement of water across a selectively permeable membrane.

What does isotonic mean?

The solute concentration is the same inside and outside the cell.

What does hypertonic mean?

There is more solute outside the cell.

What does hypotonic mean?

There is less solute outside the cell.

What are the three types of mediated transport?

• Facilitated diffusion

• Active transport

• Secondary active transport

What is facilitated diffusion?

Movement from high → low concentration using a membrane protein.

No ATP required.

What is active transport?

Movement from low → high concentration using energy.

What does ATP-powered transport require?

ATP energy.

What do channel proteins do?

Provide a passageway through the membrane for specific substances.

What are non-gated ion channels?

Channels that are always open.

What are gated ion channels?

Channels that open or close in response to a stimulus.

What is a ligand-gated channel?

A channel that opens/closes when a chemical signal binds to it.

acetylcholine

What is a voltage-gated channel?

A channel that opens/closes in response to a change in electrical voltage.

What are carrier proteins also called?

Transporters

What is a uniporter?

Moves one type of substance.

What is a symporter?

Moves substances in the same direction.

What is an antiporter?

Moves substances in opposite directions.

What is the function of a receptor protein?

To receive chemical signals and cause a response in the cell.

What happens when a ligand binds to a receptor linked to a channel?

The channel changes shape and opens or closes.

What do G-protein-linked receptors do?

Activate G proteins that lead to intracellular chemical signals and changes in cell function.

What is an enzyme?

A biological catalyst that speeds up chemical reactions.

How do enzymes speed up reactions?

By lowering activation energy.

What are the 3 characteristics of mediated transport?

Specificity, competition, and saturation

What is specificity?

A transport protein only works with specific substances.

What is competition?

Different substances can compete for the same transport protein.

What is saturation?

When all available transport proteins are occupied, so the transport rate reaches a maximum.

What is secondary active transport?

Transport that uses the energy stored in an ion concentration gradient rather than directly using ATP at the transporter.

What is an example of secondary active transport?

Na⁺ and glucose cotransport.

What is symport?

Two substances move in the same direction.

What is antiport?

Two substances move in opposite directions.

What is bulk transport?

Movement of large particles or amounts of material using vesicles

What is endocytosis?

Movement of material into the cell using a vesicle.

What are the 3 types of endocytosis?

• Phagocytosis

• Pinocytosis

• Receptor-mediated endocytosis

What is phagocytosis?

"Cell eating" — taking in large particles.

What is receptor-mediated endocytosis?

Specific molecules bind to receptors and are brought into the cell.

What is exocytosis?

Movement of material out of the cell using a vesicle.

What is a gene?

A section of DNA containing information for a functional product.

What is gene expression?

Using the information in a gene to make a functional product.

What is the basic flow of genetic information?

DNA → RNA → Protein

What is transcription?

DNA → mRNA

Where does transcription occur in eukaryotic cells?

Nucleus

What is translation?

mRNA → protein

Where does translation occur?

At ribosomes.

What is posttranscriptional processing?

Processing the initial RNA transcript to make mature mRNA.

What happens to introns during RNA processing?

Introns are removed.

What happens to exons during RNA processing?