CH 3: Cell Structures/Functions (PT 2)

(3.4-3.6)

(3.4)

What is the structure and function of the prokaryotic chromosome?

They’re SINGLE, CIRCULAR DOUBLE-STRANDED DNA molecule that CONTAINS ALL GENETIC INFORMATION NEEDED BY A CELL (or other information that’s not need

• It REPLICATES WITH THE GENOME

  • A genome is the complete set of DNA

• PASSED DOWN DURING CELL DIVISION

• They’re the MAIN DNA FOR REPLICATION, GROWTH, AND SURVIVAL

What is a nucleoid?

A REGION OF A PROKARYOTIC CELL THAT CONTAINS THE DNA

What are plasmids? What role do plasmids play in bacterial antibiotic resistance?

They’re EXTRA DNA MOLECULES that REPLICATES INDEPENDENTLY OF THE CHROMOSOME

• DOESN’T CARRY GENETIC INFORMATION

• HELPS WITH RESISTANCE AND DEFENCE (and gene transfer)

  • They help create enzymes that destroy some antibiotics (which allows them to resist medication)

How can plasmids spread between bacterial cells, and what implications does this have for antibiotic resistance?

It TRANSFERS A COPY OF A PLASMID TO ANOTHER CELL (CONJUGATION) which iNCREASES ANTIBIOTIC-RESISTANT BACTERIA

What are ribosomes? What is the structure of prokaryotic ribosomes, and how do they differ from eukaryotic ribosomes?

These are INVOLVED IN PROTEIN SYNTHESIS

• They’re like the FACTORIES THAT MAKES PROTEINS

• They’re REFERRED TO AS 70S (For PROKARYOTIC RIBOSOMES)

Why is the difference between prokaryotic and eukaryotic ribosomes medically significant?

ANTIBIOTICS THAT IMPACT THE 70S RIBOSOME DON’T EFFECT 80S (the eukaryotic ribosomes) AND VICE VERSA

• Antibiotics that impact 70S don’t affect 80S

• Antibiotics that impact 80S don’t affect the 70S ribosomes

What are cytoskeletons?

The INTERIOR PROTEIN THAT PROVIDES STRUCTURE AND SUPPORT

**Relate and define the cell membrane, cell wall, and cytoskeleton and how does each relate to each other

What are endospores, and what makes them so resilient to extreme conditions?

Endospores are DORMANT CELLS MADE BY CERTAIN BACTERIAS TO HELP IT SURVIVE HARSH ENVIRONMENTS

• Endospores STOP METABOLIC PROCESSES which makes it DORMANT, allowing it to SURVIVE LONGER

What is a vegetative cell?

It’s a cell that AFTER SURVIVING HARSH CONDITIONS, it EXITS from its DORMANT STATE and BECOMES A TYPICAL MULTIPLYING CELL

What is sporulation? What triggers the process of sporulation in endospore-forming bacteria?

Sporulation is ENDOSPORE FORMATION

• It’s triggered when ENDOSPORE-FORMING BACTERIA EXPERIENCE LIMITING AMOUNTS OF CARBON OR NITROGEN

Describe the steps involved in sporulation, including the formation of the septum and the roles of the two compartments.

1. When it starts, the CELL STOPS GROWING AND DUPLICATES DNA

2. Then a SEPTUM FORMS — this will DIVIDE THE CELL ASYMMETRICALLY

3. LARGER compartment (the “mother cell”) ENGUFS SMALL COMPARTMENT which FORMS DOUBLE MEMBRANE (they each have their own roles in creating endospore)

4. The SMALL compartment BECOMES A FORE-SPORE (which becomes the core of the endospore)

5. MOTHER CELL DEGRADES, ENDOSPORE IS RELEASED

How do the various layers of the endospore protect it from damage?

The CORTEX of the endospore PROTECTS IT FROM EFFECTS OF HEAT

• The core of the endospore has a PROTEIN that BINDS TO DNA and PROTECTS FROM DAMAGE

What is germination? How is the process of germination triggered, and what are the key steps involved?

It’s when an ENDOSPORE EXITS DORMANT STATE and BECOMES A VEGETATIVE CELL

• It starts to germinate when it’s EXPOSED TO CERTAIN CHEMICALS

  • When it becomes exposed, the endospore absorbs water and it swells, then the vegetative cell grows out

How does the core wall transform during the process of germination?

The core wall BECOMES A PEPTIDOGLYCAN LAYER of the VEGETATIVE CELL

(3.5)

What are organelles? What is the function of it?

A CELL STRUCTURE that has ONE OR MORE SPECIFIC JOBS in the cell

• There are different kinds of organelles in the eukaryotic cell (NOT PROKARYOTES cause those don’t have membrane-bound organelles)

• It allows the cell to PERFORM COMPLEX FUNCTIONS IN SEPARATED AREAS

Which organelle contains the cell's genetic information?

The NUCLEUS

How do protozoa and animal cells differ from fungi and plant cells in terms of their structural features?

• Animal cells and Protozoa DON’T HAVE CELL WALLS

• Fungi and Plant cells HAVE CELL WALLS

How is the structure of the eukaryotic cytoplasmic membrane similar to that of prokaryotic cells?

It has a CYTOPLASMIC MEMBRANE

What role do membrane proteins play in cellular processes?

It could be INVOLVED IN TRANSPORT or MAINTAIN CELL INTEGRITY

What is a receptor and ligand? How do receptor-ligand interactions contribute to cell communication?

Receptors: PROTEINS on CELL SURFACE that BINDS TO LIGANDS TO TRIGGER RESPONSES

Ligand: Thing that BINDS TO RECEPTORS

• Contributes to cell communication through SIGNALING

  • The ligands are the “messages” that CONNECT to the receptors and tells them what to do so that they could execute the action

What are aquaporins?

They are PROTEINS that acts as a WATER CHANNEL IN CELL MEMBRANES

• helps MAINTAIN WATER BALANCE IN CELLS, tissues, and organs

What are channels?

PROTEINS that ALLOWS SPECIFIC IONS OR SMALL MOLECULES TO EXIT/ENTER the cell

• It can open or close based on the environment that it’s it

  • If there’s too much of something, it might not allow that certain ion/molecule to pass through (which means that it would be closed)

• Notice how the channel proteins can just let certain molecules in/out FREELY

What are carriers?

PROTEINS that BIND TO SPECIFIC MOLECULES and ACTIVELY TRANSPORT THEM THROUGH THE CELL MEMBRANES

• These bind to a molecule/ions, change it’s shape, then transports it through the cell membrane

What are the different types of transport proteins in eukaryotic cells, and how do they facilitate movement across the cytoplasmic membrane?

It’s AQUAPORINS, CHANNELS, OR CARRIERS

• Aquaporins allow water to pass through

• Channels allow small molecules/ions to let them IN/OUT of the cell membrane FREELY

• Carrier take a SPECIFIC MOLECULE/ION, change its shape, then transport it

  • Does some kind of modification

⭐️ How does facilitated diffusion differ in multicellular organisms compared to unicellular organisms? (Look at bio notebook)

For PROKARYOTES, it RARELY USES FACILITATED DIFFUSION because the inside has high concentration of solutes, making facilitated diffusion useless

For EUKARYOTES, on the other hand, it MUST USE FACILITATED DIFFUSION because of their LARGER SIZE and how it ALLOWS HARDER-TO-PASS MOLECULES to MOVE ACROSS THE MEMBRANE

• It’s much more complex to move nutrients in/out of a eukaryote, that’s why they use facilitated diffusion

What is the role of endocytosis in the cell? What are different types of endocytosis (3 — PRP)?

Endocytosis is a process where a CELL ENGULFS LARGE SUBSTANCES (that won’t pass through a transport protein) BY SURROUNDING THEM WITH ITS MEMBRANE, which creates a VESICLE TO BRING INSIDE

• There’s pinocytosis

• Receptor-mediated endocytosis

• Phagocytosis

What is pinocytosis?

It’s a type of endocytosis that TAKES IN LIQUIDS AND ANY DISSOLVED SUBSTANCES

• It’s like it’s DRINKING and taking in the liquids

What is receptor-mediated endocytosis?

it’s a type of endocytosis where SPECIFIC MOLECULES BIND to RECEPTORS and TRIGGERS FORMATION OF VESICLE AND GETS ENGULFED (and it’s surrounded by membrane, forming a vesicle)

What is phagocytosis?

Type of endocytosis where a CELL ENGULFS LARGE PARTICLES (like bacteria) TO DIGEST THEM AND BREAK IT DOWN

• ETC: white blood cells eats and destroys harmful bacteria

• When looking at the photo, we can see that after eating the large particles, it breaks it up and lets it go

• PHAGOCYTES (cell type of the body’s defense system)USE THIS

What is exocytosis? How is it different from endocytosis?

Exocytosis is when CELLS “THROW UP” MATERIALS

• instead of swallowing small molecules or ions (endocytosis), exocytosis is throwing it up

• When thinking about “EXO” you want to THROW UP because of how hot the members are

• They EXPEL THINGS TO REMOVE WASTE AND RELEASE IMPORTANT MOLECULES

(3.6)

What are ribosomes?

Ribosomes CREATE PROTEINS by ASSEMBLING AMINO ACIDS DURING TRANSLATION

• Ribosomes are created my the NUCLEOLUS

What’s the difference between eukaryotic and prokaryotic ribosomes? Why’s it medically relevant?

Eukaryotic ribosomes are made of 80S (made of 60S and 40S subunits) while the prokaryotic ribosomes are 70S

• It’s medically important because scientists can create an antibiotic that can kill a bacteria (the prok) without harming the animal cells (the Euk)

  • So basically, things that affect the prok ribosomes STRUCTURALLY WONT AFFECT EUK RIBOSOMES

What is a cytoskeleton? What are the THREE main compartments of the sky cytoskeleton? (“MIA”)

Cytoskeleton is the INTERNAL STRUCTURE that ACTS AS SOMETHING THAT GIVES IT SHAPE AND STRUCUTRE

• There are:

  • Microtubules

  • Intermediate filaments

  • Actin filaments

What is a microtubules? Why are microtubules essential for cell division?

Microtubules are like the TRAIN TRACKS WHICH ALLOWS MOLECULES TO TRAVEL TO DIFFERENT AREAS WITHIN THE CELL with the help of motor proteins

• it HELPS KEEP SHAPE AND DIVIDE PROPERLY

• MOTOR PROTEINS HELP FACILITATE THIS TRAVEL

• They are essential for cell division because microtubules CREATE MITOTIC SPINDLES WHICH DIVIDES DUPLICATED CHROMOSOMES

  • No mitotic spindles → no cell reproduction

What are intermediate filaments? What function do intermediate filaments serve in a cell?

Intermediate filaments are structures in eukaryotic cell that STRENGTHEN THE CELL MECHANICALLY.

• It gives MECHANICAL SUPPORT which ALLOWS CELLS TO RESIST PHYSICAL STRESS

What are actin filaments? How do actin filaments contribute to cell movement?

CYTOSKELETAL STRUCTURES (of euk cells) that ALLOW MOVEMENT WITHIN CELL and SHAPE CHANGES

• The actin ASSEMBLE AND DISASSEMBLE QUICKLY TO CREATE FORCE TO DRIVE MOTION

What is a cilia?

SHORT, HAIR-LIKE STRUCTURES that MOVE TO HELP WITH MOVEMENT

How is the structure of a eukaryotic flagellum different from its prokaryotic counterpart?

Eukaryotic flagellum USES ATP AS A SOURCE OF ENERGY while Prokaryotic flagellum uses PMF (proton motive force)

• Unlike PF where the flagella ROTATES (acting like a helicopter propeller) to go to a different direction, EF MOVES USING A WHIP-LIKE MOTION (smooth, blinding motion)

• When looking at the photo, the PF looks more like a slump dick (which could be rotated around) while the EF looks like a hard boner (it moves like a whipping motion)

• The flagella for EUKARYOTES ARE 9+2 ARRANGEMENT

  • 9 pairs of microtubules surrounded by 2 individual microtubules

What is the difference between the protein structures of a eukaryotic cell and prokaryotic cell?

Eukaryotes have:

• CYTOSKELETON - it's more well developed

• FLAGELLA (that are more like a hard dick than a limp one — this allows for the flagella to move in a “whip” motion

• CILIA

• 80S ribosome