AP Biology Unit 2 Cell Structure Exam Review

What is the structure and function of the ribosome?

Ribosomes consist of RNA and proteins and they help with synthesizing proteins. There is a large and small subunit.

How does the structure of the ribosome aid in the function?

The structure of the ribosome allows proteins to be made inside or outside the cell.

What are the three types of RNA involved in the structure or function of the ribosome?

messenger (mRNA) is transcribed from DNA and carries the message to cytoplasm where ribosomes translate it into a polypeptide
transfer (tRNA): carries a specific amino acid to the correct position on the ribosome using its anticodon to match to the codon on the mRNA.
ribosomal (rRNA): joins with proteins to make ribosomes where translation occurs to form a protein.

How does the ribosome demonstrate a common ancestry of all known life?

All life forms have ribosomes.

What is the structure and function of the rough ER?

The rough endoplasmic reticulum is a series of connected flattened sacs, part of a continuous membrane organelle within the cytoplasm of eukaryotic cells, that plays a central role in the transport of proteins made on its attached ribosomes.

How does the structure of the rough ER aid in the function?

It allows for the production, folding, quality control and dispatch of some proteins.

What is the structure and function of the smooth ER?

It is a network of membranes called cisternae. They are held together by the cytoskeleton. The function of the smooth ER is to help with synthesizing lipids, phospholipids as in the plasma membrane and steroids.

How does the structure of the smooth ER aid in the function?

Smooth ER is a network of membranes that separate the cell into compartments for metabolic processes. Smooth ER functions in the synthesis of lipids in most cells, the breakdown of toxins in liver cells, and storage and release of Ca++ in muscle cells. Keeping the enzymes or molecules needed for a specific chemical pathway together in a specific area is more efficient.

What is the relationship between the ribosome and the rough ER?

Ribosomes attach to the rough ER and insert the proteins being made into the rough ER for intracellular transport to Golgi for modification and export

What is the structure and function of the Golgi?

The Golgi apparatus is a central intracellular membrane-bound organelle. Its key function is to traffic, process, and sort newly synthesized membrane and secretory proteins and lipids.
Note: any of the names (Golgi Bodies/Apparatus/Complex) could appear on the exam so be knowledgeable about the different ways you might see this structure

How does the structure of the Golgi aid in the function?

It packages proteins into vesicles so they can be transported in or out of the cell.

What is the structure and function of the mitochondria?

It is membrane bound organelle that consists of an outer and inner membrane that produces energy for the cell by breaking down carbohydrates and producing ATP.

How does the structure of the mitochondria aid in the function?

The inner membrane folds increase surface area which allows for a lot of ATP to be formed and quickly.

Note: Mitochondria is the "powerhouse of the cell" is NOT an appropriate response on the AP exam

What is the structure and function of the lysosome?

It is a small membrane bound organelle that has an acidic interior. The purpose of the lysosome is to break down excess or worn-out cell parts. They can also aid in destroying invading viruses and bacteria.

How does the structure of the lysosome aid in the function?

The membrane surrounding the lysosome keeps proteolytic enzymes separated from the rest of the cell. Proton pumps in lysosomal membranes create acidic interior for digestion.

What is the structure of the vacuole?

A membrane-bound organelle that is generally small and circular in structure.

What is the function of the food vacuole?

It is used for storage of nutrients, water or waste.

What is the function of the central vacuole?

In plants it helps to maintain water balance.

What is the function of the contractile vacuole?

To maintain the constant osmotic pressure in the fluids of an organism by the control of water and salt concentrations in a well-balanced way so that the cell doesn't get ruptured due to cytolysis. (Osmoregulation)

What is the structure and function of a chloroplast?

Plant cell organelle that is oval-shaped and has an outer membrane and inner membrane folded into thylakoid sacs stacked into grana that converts light energy into chemical energy through the process of photosynthesis.

How does the structure of the chloroplast aid in the function?

Thylakoid sacs make compartments to create the H+ gradient needed for ATP production during the light dependent reactions.

How does the endoplasmic reticulum provide mechanical support?

it can help maintain cell shape by interacting with the cytoplasmic matrix

How does the endoplasmic reticulum aid in protein synthesis?

it has ribosomes on it to perform protein synthesis

How does the endoplasmic reticulum aid in intracellular transport?

it will transport materials through vesicles

How does the lysosome aid in intracellular digestion?

it will break down food using its enzymes

How does the lysosome aid in recycling the cell's organic materials?

it will breakdown old or broken down organelles using its hydrolytic enzymes

How does the lysosome aid in apoptosis (programmed cell death)?

lysosomes can release enzymes called proteases into the cytosol that will start the cascade of apoptosis

How does the vacuole assist in storage of macromolecules?

provides a lot of space for storage of many types of macromolecules

How does the vacuole provide turgor pressure?

the vacuole will fill up with water that pushes on the cell membrane which then pushes on the cell wall causing turgor pressure

What is the structure of the inner membrane (cristae) of the mitochondria?

highly folded membranes

How does that contribute to the function of the inner membrane (cristae) of the mitochondria?

highly folded membranes allow for more surface area to complete the oxidative phosphorylation of cellular respiration

How is the chloroplast organized?

many thylakoid membranes stacked to increase surface area for light reactions in photosynthesis

What is embedded in the chloroplast and how does it aid in the function of the chloroplast?

photosystems containing chlorophyll to absorb sunlight

Where do the light-dependent and light-independent reactions take place?

Photosystems and ETC for the light independent reactions are located in the thylakoid membranes. Light independent reactions happen in the stroma.

How does the thylakoid aid in energy capturing?

Chlorophyll containing photosystems are located in thylakoid membranes.and numerous thylakoid sacs create more surface area to collect more light

How does the thylakoid aid in energy storing?

Electron transport proteins are located in thylakoid membranes.and transport of H+ ions into the thylakoid space creates the H+ gradient needed for ATP production during the light dependent reactions.

Where does the citric acid cycle (Krebs cycle) in cellular respiration take place?

Matrix of mitochondria

Where does the electron transport chain in cellular respiration take place?

Proteins for ETC are located in cristae membranes

Where does the electron transport chain in photosynthesis take place?

Proteins for ETC are located in thylakoid membranes

Where is ATP synthesized in cellular respiration?

2 ATP made during glycolysis in cytoplasm
2 ATP during Krebs cycle in matrix of mitochondria32 made by ETC/ATP synthase on matrix side of cristae

Where is ATP synthesized in photosynthesis?

Stroma of chloroplast

How does surface area to volume ratio affect the size of the cell?

The surface area of the plasma membrane must be large enough to adequately exchange materials. .As a cell increases in size its surface area/volume decreases, limiting how big it can get.

What type of surface area to volume ratio is most favorable for cells?

A higher surface area-to-volume ratio is more efficient for exchange of materials with the environment

Calculate the surface areas for the following "cell": Sphere with a radius of 2

4 X 3.14 X 2^2 = 50.27

Calculate the surface areas for the following "cell": Cube with a side length of 3

6 X 3 X 3 = 54

Calculate the surface areas for the following "cell": Rectangular solid with dimensions of 2 x 3 x 4

(2 X 4 X 3) + (2 X 4 X 2) + (2 X 3 X 2) = 24 + 16 + 12 = 52

Calculate the surface areas for the following "cell": Cylinder with a radius of 2 and height of 4

(2 X 3.14 X 2 X 4) + (2 X 3.14 X 2^2 ) = 50.24 + 25.12 = 75.40

Calculate the volumes for the following "cell": Sphere with a radius of 2

4/3 X 3.14 X 2^3 = 33.51

Calculate the volumes for the following "cell": Cube with a side length of 3

3 X 3 X 3 = 27

Calculate the volumes for the following "cell": Rectangular solid with dimensions of 2 x 3 x 4

2 X 3 X 4 = 24

Calculate the volumes for the following "cell": Cylinder with a radius of 2 and height of 4

3.14 X 2^2 X 4 = 50.27

Calculate the surface area to volume ratio for the following "cell": Sphere with a radius of 2

50.24/33.5 = 1.5:1

Calculate the surface area to volume ratio for the following "cell": Cube with a side length of 3

54/27 = 2:1

Calculate the surface area to volume ratio for the following "cell": Rectangular solid with dimensions of 2 x 3 x 4

52/24 = 2.2:1

Calculate the surface area to volume ratio for the following "cell": Cylinder with a radius of 2 and height of 4

75.4 /54.4 = 1.5:1

What SA/V ratio makes the cell the most efficient?

Cells with the greatest SA/Volume ratio are the most efficient at transporting nutrients in/waste out.

How does an increase of surface area affect the increase in volume?

As cells increase in size volume increases faster than surface area. The relative surface area decreases and the demand for internal resources increases.

How can a cell increase surface area without increasing the volume?

Folded membranes

How can an increase in surface affect heat exchange?

Higher surface area = higher heat exchange

Identify and describe two examples of specialized surfaces for exchanging materials with the surrounding environment

Root hair extensions on roots increase absorption on nutrients and water from soilMicrovilli extensions on cells that line the gut increase absorption of nutrients in small intestine
Numerous tiny air sacs (alveoli) increase gas exchange in lungs

Identify and describe two examples of strategies that organisms use to obtain nutrients and eliminate wastes.

Obtain nutrients - Autotrophs (phototroph or chemotroph) and heterotrophs
Eliminate wastes - removal of nitrogenous wastes varies - ammonia, urea, uric acid

What are the components of the cell membrane?

phospholipids, proteins, glycoproteins, glycolipids, cholesterol

Describe the orientation of the components for the structure of the phospholipid.

hydrophilic/polar phosphate heads orient toward aqueous environments (inside and outside cell) while hydrophobic/nonpolar fatty acid tails face inward away from water

Regarding a cell, if the internal conditions are aqueous and the external conditions are aqueous, describe the structure of the cell membrane.

Phospholipid bilayer, hydrophilic heads pointing out toward the external AND the internal, and tails facing the inside of the membrane.

Regarding a cell, if the internal conditions are nonaqueous and the external conditions are aqueous, describe the structure of the cell membrane.

Single layer of phospholipids with heads facing outward and the tails inward

Regarding a cell, if the internal conditions are aqueous and the external conditions are nonaqueous, describe the structure of the cell membrane.

Single layer of phospholipids with tails facing outward and the heads inward

Regarding a cell, if the internal conditions are nonaqueous and the external conditions are nonaqueous, describe the structure of the cell membrane.

Heads bunched in toward one another with tails facing outward

How does the phospholipid bilayer maintain the internal environment of a cell?

The cell membrane acts as a barrier between the interior and exterior cellular environment It is selectively permeable and controls and maintains a balance of molecules that are present in the cell, such as proteins and ions

What are the different types of membrane proteins?

Integral (intrinsic) proteins -Permanently embedded in plasma membrane, contain both phobic and philic parts, interact with hydrophobic core of bilayer; act as carrier proteins, channels, or enzymesPeripheral (extrinsic) proteins - Located on inner or outer surface of plasma membrane; act as receptors, surface antigens

Describe six functions of membrane proteins.

~ Attachment to cytoskeleton and extracellular matrix. Maintains cell shape and stabilizes cytoskeleton.~ Intercellular joining. Proteins on adjacent cells hook together, briefly, for cell interaction/sharing.~ Signal transduction.~ Enzymatic activity. ~ Cell-cell recognition.~ Transport.

How does the polarity of the membrane protein affect its orientation in the membrane?

polar amino acids are on the extracellular side and intracellular side, while nonpolar proteins are running through hydrophobic core of the membrane

How does the membrane protein maintain the internal environment of a cell?

Controls what enters/leaves cell. it allows certain ions and water to pass through the membrane into and out of the cell

Define the fluid mosaic model.

The cell membrane is a mosaic of protein molecules floating within a fluid bilayer of phospholipids.

What is the function of steroids in the plasma membrane?

Cholesterol helps to control membrane fluidity and allows the cell membrane to adapt to different environmental conditions; at moderate temps cholesterol will reduce membrane fluidity and at low temps it stops the phospholipids from packing too closely together

What is the function of glycoproteins in the plasma membrane?

Important in cell to cell recognition and adhesion

What is the function of glycolipids in the plasma membrane?

Maintain stability of cell membrane and serve in cellular recognition

What types of materials can easily pass through the membrane?

Oxygen and carbon dioxide

Why does this type of material easily pass through the membrane?

Small, nonpolar molecules can easily pass through the nonpolar fatty acid tail portion of the membrane

What types of materials require a protein to pass through the membrane?

Glucose, ions

Why do glucose and ions require a protein to pass through the membrane?

They are large and/or polar molecules that cannot easily pass through the nonpolar region of the membrane

What types of materials require a vesicle for export or a food vacuole for import?

bulk transport or larger molecules; examples: neurotransmitters and starches

Why do larger molecules require bulk transport?

too many of them to efficiently cross the membrane or too large to fit through the membrane

Where are plasma membranes found in a cell?

surrounding the cell and also around many different organelles

What types of cells have a cell wall?

Fungi, plants, prokaryotes

How does the cell wall maintain cell structure?

provides a framework for the cell through an interconnected network of cellulose fibers, structural proteins, and other polysaccharides that help maintain the shape

How does the cell wall protect the cell from hypotonic solutions?

Cell walls prevent plant cells from bursting when placed in hypotonic solutions.

How do materials pass through the cell wall?

plasmodesmata in plants

What composes the cell wall of a plant?

cellulose

What composes the cell wall of a fungi?

chitin

What composes the cell wall of a prokaryote?

peptidoglycan

What is passive transport?

Type of membrane transport that does not require energy to move substances down their concentration gradient across cell membranes.

Identify two examples of passive transport.

Simple diffusion- movement of oxygen from alveoli into blood stream. Facilitated diffusion - movement of glucose across a cell membrane via a carrier protein. Osmosis- movement of water across a cell membrane with the help of aquaporins

What is active transport?

Type of membrane transport that requires energy to move substances across cell membranesagainst their concentration gradient

Identify two examples of active transport.

Sodium-Potassium pump- Uses energy from ATP to move 3 Na+ ions out of cell and 2 K+ ions into cellUsed to create membrane potential in animal cellsEndo/Exocytosis- Uses energy and membrane vesicles to transport molecules across cell membranes

What is required for active transport?

Energy (ATP)

What is a concentration gradient?

When the amount or concentration of particles is higher in one area than another

How is a concentration gradient maintained?

Particles moving through transport or channel proteins

What causes a concentration gradient?

Differences in the amount of substances on either side of a membrane

What is endocytosis?

When large particles enter a cell in vesicles.

Describe the three types of endocytosis.

Phagocytosis (cell "eating"), pinocytosis (cell "drinking"), receptor-mediated endocytosis (receptors on cell will allow for only specific molecules to be taken into vesicles; ex: cholesterol)