bio 1.3 & 1.4

Prokaryotic cells

Cells that lack a defined nucleus and membrane-bound organelles.

Eukaryotic cells

Cells that have a defined nucleus and membrane-bound organelles.

Nucleus =

The organelle that contains the cell's genetic material and controls cellular activities

Ribosome

Makes proteins

Rough endoplasmic reticulum (Rough ER) =

Has ribosomes; involved in protein production/processing

Golgi apparatus =

An organelle that modifies, sorts, and packages proteins for secretion or delivery to other organelles

Mitochondrion

An organelle that produces ATP through cellular respiration, often referred to as the powerhouse of the cell.

Lysosome =

An organelle that contains digestive enzymes to break down waste materials and cellular debris

Transcription

The process of copying a segment of DNA into messenger RNA.

Translation

The process of decoding messenger RNA to synthesize proteins.

Selective permeability

The property of a cell membrane that allows some substances to pass through while blocking others.

Simple diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration without assistance.

Facilitated diffusion

The process of moving molecules across a membrane through a protein channel, assisted by specific transport proteins.

Osmosis

The diffusion of water molecules across a selectively permeable membrane.

Hypertonic solution

A solution with a higher concentration of solutes outside the cell, causing the cell to lose water and shrink.

Isotonic solution

A solution with equal concentrations of solutes inside and outside the cell, resulting in no net movement of water.

Hypotonic solution

A solution with a lower concentration of solutes outside the cell, causing the cell to gain water and swell.

Passive transport

The movement of substances across a cell membrane without the use of cellular energy.

Active transport

The movement of substances across a cell membrane that requires energy, often against a concentration gradient.

Na⁺/K⁺ ATPase

An enzyme that pumps sodium ions out of the cell and potassium ions into the cell, maintaining their gradients.

Beta-cell insulin pathway

The process in which glucose enters a beta-cell, stimulates insulin synthesis, and leads to insulin release into the bloodstream.

Nucleoid =

bacterial DNA region, NOT a nucleus / organelle

Cell membrane =

Present in all cells

Made of phospholipids

Cell wall =

Outside layer of bacteria

Flagella =

Allows bacteria to be propelled around its liquid medium

Smooth Endoplasmic Reticulum (ER) =

No ribsosomes

Cytoskeleton =

Structure + movement / transport

What are the three types of cytoskeleton?

• Microtubules → transport + cell division; "railroad tracks"

• Intermediate filaments → support/scaffolding

• Actin/microfilaments → support/attachment to membrane

What happens during protein synthesis?

1. DNA contains the gene.

2. mRNA is made.

3. mRNA leaves nucleus.

4. Ribosome reads mRNA.

5. Protein is made.

6. Protein enters rough ER.

7. Vesicle carries it to Golgi.

8. Golgi processes/routes it.

9. Vesicle goes to membrane.

10. Protein is released outside.

What is Transcription?

DNA → mRNA

What is Translation?

mRNA → protein

What is the protein pathway?

DNA → mRNA → ribosome → rough ER → vesicle → Golgi → vesicle → outside cell

What is selective permeability?

When the membrane allows certain substances through but restricts others

Whether something can cross depends on things like:

• size

• polarity/charge

• membrane proteins

What are non polar substances?

Non polar substances are molecules that do not have a significant charge difference across their structure, allowing them to pass through the cell membrane / phospholipid bilayer more easily

They tend to be hydrophobic and do not interact well with water

What are polar substances?

Polar substances are molecules that have a significant charge difference across their structure, making them hydrophilic and often unable to pass through the cell membrane / phospholipid bilayer easily

• They require a membrane protein

• They tend to interact well with water

What is passive transport?

NO ATP

High → Low concentration

What is simple diffusion?

When substances are able to move directly though the membrane

High → Low

No energy

• Example: substances such as steroid molecules can diffuse through the membrane.

What is facilitated diffusion?

Still HIGH → LOW

but requires a membrane protein

• Examples:

  • Na⁺ → channel

  • Glucose → carrier

Using a protein does NOT automatically mean active transport

If it moves high → low without ATP = passive/facilitated diffusion

What is osmosis?

The movement of water across the membrane

• when solving this: look at the solute concentration → water moves toward the side with more solute