AP Biology Chapter 6 & 7 TEST

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotes:

• No organelles or nucleus

• Came before eukaryotes

• DNA is in a region called the nucleoid

• Smaller than eukaryotes

• ex: bacteria cells

• domain: bacteria and archaea

Eukaryotes:

• Has organelles and nucleus

• Came after prokaryotes

• DNA is in the membrane bound nucleus

• Bigger than prokaryotes

• ex: plant and animal cells

• domains: animalia, plantae, fungi, and protista

In common:

• Cytoplasm

• Chromosomes

• Plasma membrane

• Ribosomes

Why are cells so small?

Only a limited amount of a substance can pass a membrane wall per second.

• so surface area: volume is crucial

As cell size increases, volume grows proportionally more than surface area(SA is ² and volume is ³)

• smaller the object, the GREATER the SA:V

• A bigger SA:V facilitates the exchange of materials between the cell and its environment

What is the endosymbiosis Theory? Provide evidence for this theory

chloroplasts and mitochondria were once free living bacteria(prokaryotes)

then they were engulfed by a ancestral eukaryote, which evolved into a endosymbiont

• a endosymbiont is a cell that lives within another cell(this is good for evolutionary, mitochondria provided energy and the host would provide nutrients)

evidence:

• they grow and reproduce(semi-autonomous organelles)

• proteins from from free ribosomes but some come from their own ribosomes

• own circular chromosomes(direct synthesis of proteins produced by their own ribosomes)

• double membrane

Plant vs animal cell organelles

Animal cells do not have(does not have definite shape because lack of cell wall):

• Chloroplasts

• Central vacuole

• Cell wall

• Plasmodesmata

Plant cells do not have(has definite shape because of cell wall):

• Lysosomes

• Centrioles

• flagella(in some plant sperm)

plant cells have both Chloroplasts and mitochondria, also cell wall and plasma membrane

plant cells: rigid, large vacuole

animal cells: flexible membranes, many vacuoles

nucleus

Both animal and plant cell

• function: protects DNA, controls gene expression

• structure: nuclear envelope, double membrane, membrane has pores to allow macromolecules to pass through

• contains nucleolus

nuceolus

Both animal and plant cell

• function: ribosome production, Build ribosome subunits from rRNA and proteins, Exits through nuclear pores to cytoplasm and combine to form functional ribosomes

mitochondria

Both animal and plant cell

• Function: cellular respiration, generates ATP(powerhouse of the cell)

  • Breaks down sugars, fats, and other fuels, In the presence of oxygen(aerobic respiration)

  • break down larger molecules into smaller to generate energy=catabolism

• structure:

  • 2 membranes(smooth outer, highly folded inner membrane), both are phospholipid bilayers.

  • Internal fluid-filled space: Mitochondrial matrix, contains: DNA, ribosomes, and enzymes

binary fission: dividing of mitochondria

Rough ER

Both animal and plant cells

function: produces proteins for export out of cell

• protein secreting cells

• packaged into transport vesicles for export

structure: has ribosomes attached

Smooth ER

Both animal and plant cell

function: membrane production, synthesizes lipids, hydrolysis(breaks down toxins), storage of calcium ions

structure: doesnt have ribosomes

Golgi apparatus

Both animal and plant cells

function:

• Finishes, sorts, tags, and ships cell products(Like UPS department)

• Ships products in vesicles( ‘UPS trucks’ )

structure:

• cis side- where it receives transport vesicles

• trans side- where it secretes it

Lysosomes

In only animal cells

function:

• Little “stomach” of the cell(Digest macromolecules)

• “Clean up crew” of the cell(Clean up broken down organelles)

structure:

• Vesicles of digestive enzymes(works best at pH 5

lysosomes help kill cells when needed(apoptosis)

ex: tadpoles tails going away after grown legs

peroxisomes

Both animal and plant cell

function:

• breakdown fatty acids to sugars(easier to transport and use as energy source)

• Detoxify cell(detoxifies alcohol and other poisons

• Produce peroxide(H2O2)(must break down to water because its toxic to us)

digestive enzyme sac

Vacuoles and vesicles

function:

• 'little “transfer ships”

• Food vacuoles- phagocytosis, fuse with lysosomes

• contractile vacuole- in freshwater protists, pump excess H2O out of cell

• Central vacuole- in many mature pant cells

plant cells- has one large vacuole(storage, important for plant growth)

animal cells- has many vacuoles

Chloroplast

In plant cells

function:

• stores chlorophyll

• photosynthesis(uses sunlight to create energy)

structure:

• 2 membranes

• stroma, inner fluid space(contains DNA, enzymes, ribosomes)

• thylakoids, membrane sacs where ATP is created

• granum, stack of thylakoids

can divide and change shape

Ribosomes

Both plant and animal cells

function: protein production

structure: rRNA and protein, 2 subunits combine, Doesn't have a membrane which makes it not really a organelle

types: free(found in cytosol), bound(found on ER)

Centrioles

In animal cells

function: help organize mitotic spindle fibers during cell division.

Plasmodesmota

In plant cells

function:

• connection between neighboring cells to share nutrients and genetic information

• allows things to travel between cells without having to go through membranes

structure:

• channel that connects plant cells

How are various vesicles and macro molecules transported in the golgi apparatus?

Arrival:

• the vesicles arrive and fuse to the cis-side of the golgi apparatus

• they then release into the lumen

Middle:

• cargo is moved through the cisternae and this is where enzymes will perform modifications(lipids, proteins, soleble proteins)

• while those are moving towards the trans-side, there are escaped ER resident and membrane recycling that will go backwards

End:

• once they get to the trans-side they will be sorted based on their molecular tag and then transported to their specialized areas

What causes Tay Sachs disease?

It is a rare genetic condition passed from parent to child

• caused by the absence of an enzyme that helps break down fatty substances

• lysosomal disease: a lipid digesting enzyme is missing or inactive, brain accumulates undigested materials

these fatty substances called, gangliosides, build up to toxic levels in the brain and spinal cord and affect the function of the nerve cells.

• symptoms start to show around 3-6 months old

• prognosis is very short life

• can lead to seizures, paralysis, loss of hearing

What organelles make up the endomembrane system? + acronym

• Plasma membrane

• Nuclear envelope

• Endoplasmic reticulums

• Golgi apparatus

• Lysosomes

•Vacuoles

• Vesicles

Saying: Pink Notebooks Ensure Good Learning Very Vividly

What is the pathway taken by a newly synthesized protein that will be secreted from the cell?

1. Rough ER-

• initial folding and modifications are here

3. golgi apparatus-

• the vesicle will fuse with the cis-side and go through modifications on the way to the trans-side

4. secretory vesicle -

• protein is packaged into a vesicle and transported to the plasma membrane

5. plasma membrane-

• The vesicle fuses to membrane and releases into the extracellular space(exosytosis)

What is the fluid mosaic model? Be able to identify the components in a cell membrane diagram. What makes up cell membranes?

Proposed model of the plasma membrane by S.J. Singer and G.L. Nicholson

• fluid: it is able to move side to side and has a oil like consistency

• Mosaic: it has a variety of different components like proteins and carbs that are embedded in the bilayer

What makes up the membrane?

1. phospholipids-

• this is the framework for the bilayer, has hydrophobic tails and hydrophilic heads

2. Proteins-

• “the workers”

• there is integral, which act as pumps and channels across the membrane. there is also periphral, which act as signals and structure support on the outside of the membrane

3. cholesterol-

• “buffers”

• located within the phospholipids, controls the fluidity of the membrane making sure it doesn’t get to liquid in the warmth and freeze in the cold

4. carbohydrates-

• found on the exterior of the membrane

• attached to the glycoproteins or glycolipids

• act as cell to cell recognition, which help immune cells track foreign materials

What does cholesterol do for the cell membrane?

1. Regulates Fluidity:

• At high temperatures, it restrains phospholipid movement, making the membrane less fluid and more stable.

• At low temperatures, it disrupts tightly packed fatty acid tails, preventing the membrane from freezing or becoming too rigid.

What is amphipathic? Why is this important for cell membranes?

It means it has both hydrophilic and hydrophobic regions, like a phospholipid

Its important because it forms a layer which protects the inside of the cell from the outside

It also controls what comes in and what goes out of the cell(blocks large and polar molecules)

What do unsaturated fatty acids do to the cell membrane in terms of fluidity?

They increase fluidity because:

• they have kinks with double C=C bonds

• this causes them to not be able to pack closely together

  • these weaken the hydrophobic and van Der Waals interactions, allowing lipids and proteins to move more freely

What is the primary function of polysaccharides attached to glycoproteins and glycolipids of animal cell membranes?

They are there for cell to cell recognition

• they have their own “finger print” so cells can identify each other

• this helps the immune system know whether a cell is their own or a foreign cell

they also help in bonding of cells to make tissues to add a protective barrier against damage

What key element impacts evolution of cell membranes?

• The earliest membranes were likely composed of simple fatty acids, which easily collapse in the presence of salt and magnesium ions found in early oceans. This hostile environment forced membranes to incorporate stabilizing molecules to survive.

• natural selection, all components from membranes evolve from natural selection

How is it that lipids and proteins can move laterally in membranes?

• Because of the weak hydrophobic interactions within the middle

• The core of the membrane is formed by hydrophobic fatty acid tails held together by relatively weak van der Waals/dispersion forces rather than rigid covalent bonds. This allows molecules to slide past one another easily

• it has a consistency like olive oil

• has unsaturated fatty acids which allow it to be fluid

• floating free parts like the integral proteins just sit comfortably within the fluid layer

What kind of molecules pass through the cell membrane most easily?

Smaller and non polar molecules

• like oxygen, CO2, fats and lipids

• Nonpolar and small molecules blend right into this lipid core without needing energy or protein channels because the inside is non polar

what struggles to pass:

• Ions and Charged Particles: Sodium, potassium, calcium, and chloride are repelled by the hydrophobic core and require protein channels or pumps.

• Large Polar Molecules: starch and proteins, Glucose and amino acids are too big and polar to slip through unassisted, requiring facilitated diffusion.

• Water: Water is small and polar; it crosses the lipid bilayer slowly on its own, though it moves quickly through specialized protein channels called aquaporins

What is diffusion? Be able to differentiate between active and passive transport. Be able to solve diffusion problems

Diffusion is the spontaneous net movement of particles from an area of higher concentration to an area of lower concentration, and moves until it reaches a dynamic equilibrium.

passive: high to low

active: low to high(requires ATP)

example problem:

A synthetic cell containing a 10% sucrose solution is placed in a beaker containing a 2% sucrose solution. The membrane is permeable to water but impermeable to sucrose. What will happen to the mass of the cell over time?

• Step 1: Identify the concentrations. Inside = 10% solute (90% water). Outside = 2% solute (98% water).

• Step 2: Determine where the solute is highest. The solute concentration is higher inside the cell (10% > 2%).

• Step 3: Track the water. Water moves from high water concentration (98% outside) to low water concentration (90% inside).

• Answer: Water will diffuse into the cell, causing the cell to swell and its mass to increase.

What are aquaphorins? What do they do for the cell?

these proteins act as microscopic "tunnels" that speed up the movement of water across the lipid bilayer

• Aquaporins provide facilitated diffusion, allowing water to rush into and out of the cell much faster in response to osmotic gradients

• regulates how much water enters or leaves, aquaporins help prevent cells from swelling and bursting or shrinking and shriveling

What types of solutions do plant cells prefer? animal cells?

Isotonic - equal solute, equal water

• Animal cell immersed in mild salt solution

• No difference in concentration of water between cell and environment

Problem in animal cell: none

• No net movement of water

• Flows across membrane equally, in both directions

• Cell in equilibrium

• Volume of cell is stable

Example: blood cells in blood plasma

• Slightly salty IV solution in hospital 

Plant cells:

• flaccid(water going in and out)

• They prefer turgid(water going in)

Hypotonic: less solute, more water

• High concentration of water around cell

• Problem in animal cells: cell gains water, swells and can burst

• Example: paramecium, water will continually enter paramecium cell

  • Solution: contractile vacuole(pumps water out of cell, requires ATP)

• Plant cells:

  • Turgid = full

  • Cell wall protects then from bursting

Hypertonic: more solute, less water

• Cell in salt water

• Low concentration of water around cell

  • Problem in animal cells: cell loses water and can die

  • Example: shellfish

• Solution: take up water and pump out salt 

• Plant cells:

  • Plasmolysis(plasma membrane pulls away from cell wall)= wilt

  • Can recover 

Cells with swell and burst = cytolysis

Cells with shrink and shrivel = crenation

How do ions diffuse across membranes?

active transport(against the gradient):

• ion channels using ATP

• ion pumps- Proteins use energy directly from ATP hydrolysis to pump ions across the membrane.

  • ex: sodium-potassium pump drives three sodium ions out of the cell and brings two potassium ions into the cell for every ATP used.

• co transport: These mechanisms use the established electrochemical gradient of one ion (usually Na flowing passively down its gradient) to power the movement of another substance against its gradient

What can be done to remedy diarrhea? with cotransport

a transport protein can could the “downhill” diffusion of the solute to the “uphill” transport of a second substance against its own gradient.

with diarrhea the sodium in waste never gets reabsorbed in the solon and sodium levels drop

pateints are given a solution to drink containing high concentration of salt and glucose. the solutes are taken up by sodium and glucose co transporters on the surface of intestinal cells and passed though the cell into the blood

What causes familial hypercholesterolemia?

Familial hypercholesterolemia is an inherited condition that affects the way the body processes cholesterol. As a result, people with familial hypercholesterolemia have a higher risk of heart disease and a greater risk of early heart attack.

missing LDL receptors on cell membranes, leads to build off cholesterol in blood

• Heterozygous is when it comes from one parent

• homogeneous is when it comes from both parents

inherited gene mutations that prevent the body from properly clearing low-density lipoprotein (LDL, or "bad") cholesterol from the blood.

• chromosome 19

Long FRQ:

• describe structure and function of organelles

• prokaryotes vs eukaryotes(how do prokaryotes do jobs without organelles)

• endosymbiotic theory(explain and give evidence)

• Energy Production (Mitochondria alternative): Eukaryotes use mitochondria to make ATP (cellular energy). Prokaryotes carry out the electron transport chain and make ATP directly along their plasma membrane.

• Protein Synthesis (Ribosomes): Both cell types have ribosomes to build proteins, though prokaryotes have smaller, freely floating ribosomes (70S) rather than the ones attached to an endoplasmic reticulum.

• Coupled DNA & Protein Making: In eukaryotes, DNA is transcribed into mRNA inside the nucleus, then shipped out to the cytoplasm to be translated into protein. In prokaryotes, because there is no nuclear membrane, transcription and translation happen at the same time right in the cytoplasm—ribosomes can even start building a protein while the mRNA is still being copied off the DNA.

• Genetic Storage (Nucleus alternative): Instead of a membrane-bound nucleus, a prokaryote's DNA floats in a concentrated region of the cytoplasm called the nucleoid.

Short FRQ 1:

• graph data(like labs)

• plant cells and salt water effects

• discuss water potential

water potential: potential energy of water per unit area compared to pure wate(unit is psi)

• Pure water baseline: Pure water at standard temperature and atmospheric pressure has a water potential of 0.

• Adding solutes: Dissolving solutes (like salt or sugar) binds water molecules and lowers the water potential, making it negative.

• Adding pressure: Increasing physical pressure (like turgor pressure in a plant cell) increases the water potential.

• Direction: Water moves down the gradient from higher(closer to 0) to low (more negative)

plant cells vs salt water:

• when a plant is exposed to salt water the water inside the leaves will move out(because water moves from an area of high water concentration to low concentration)

• this causes it to become frail and weak

Short FRQ 2:

• U-tube problem

• which way does water and solute go

• hypertonic vs hypotonic

• why they do it

water flows from hypotonic to hypertonic

• they do this because of osmostic pressure

• look at U-tube worksheet

Short FRQ 3:

• osmoregulation in organisms

• what do different fish do to adapt

osmoregulation: the active process by which living organisms control the balance of water and dissolved electrolytes (like salt and minerals) in their body fluids to keep their internal environment stable

• if there was no regulation then cells would burst or shrivel

Salt water fish lives in a hypertonic solution: 

Drink salt water ACTIVELY pump ions OUT; urinate less frequently

• Ions(salt) are constantly entering body

• Water is constantly leaving

Freshwater fish in hypotonic solution 

Gills ACTIVELY pump ions in; urinate frequently

• Water is constantly entering its body

• Ions are constantly leaving its body

paramecium:

• fresh water and they are hypertonic to their environment

• as a result, water fills in there cells

• to regulate they have a contractile vacuole that holds water and then pumps it out