AP Biology Unit 2 Cell Structure and Function

Vocab from Unit 2 (Cell Structure and Function) of AP Biology as based on College Board's AP Classroom.

Ribosomes and a genome

All living cells contain BLANK, reflecting the common ancestry of all life.

Ribosomes

Function: This synthesizes proteins according to mRNA sequences whose instructions are encoded and originate from the genome of the cell.

Made of rRNA and proteins

Endoplasmic Reticulum

• Provides mechanical support and plays a role in intracellular transport

• It is a network of membrane tubes within the cytoplasm of eukaryotic cells

• Has two parts, the Rough Endoplasmic Reticulum (Rough ER) and the Smooth Endoplasmic Reticulum (Smooth ER).

Found in eukaryotic cells only (plant and animal)

Rough ER

• Has ribosomes attached to its membrane

• Compartmentalizes the cell

  • Packaging the newly synthesized proteins made by attached ribosomes for possible export from the cell.

Smooth ER

• Does NOT have ribosomes attached

• Functions include detoxification and lipid synthesis

Golgi Complex

• Series of flattened membrane-bound sacs found in eukaryotic cells only.

• Involved in correct folding and chemical modification of newly synthesized proteins and packaging for protein trafficking.

Mitochondria

• Double membrane (outer membrane is smooth, and inner membrane is highly convoluted (folded), forming folds called cristae

• Functions in the production of ATP energy that eukaryotic cells can use for work.

• Cells have multiple of these

• Krebs Cycle (Citric Acid Cycle) reactions occur in the matrix

Lysosome

• Membrane-enclosed sacs found in animal cells that contain hydrolytic enzymes.

• Hydrolytic enzymes:

  • can be used to digest a variety of materials such as damaged cell parts or macromolecules.

  • Recycling of organic materials

  • programmed cell death (apoptosis)

• internal pH of 4.5-5

Vacuoles

• Membrane-bound sacs found in eukaryotic cells

• Play a variety of roles ranging from the storing of water And other macromolecules to the release of water from a cell

• Planet cells usually have a single vacuole while animal cells have multiple small and scattered vacuoles

• When the central plant vacuole is full of water, it applies pressure to the cell wall and maintains its shape (turgor pressure)

Chloroplasts

• Found in eukaryotic cells such as photosynthetic algae and plants

• Double outer membrane

• Specialized for capturing energy from the sun and producing sugar for the organism.

• Chlorophyll a is a photosynthetic pigment in chloroplasts (green!)

• Parts: thylakoid + stroma

Thylakoid

Found in chloroplasts, these are highly folded membrane compartments that are organized in stacks called grana (grana plural or granum singular).

• Light-dependent reactions occur here

• The folding of the internal membrane increases the efficiency of these reactions. (cus more surface area)

Stroma

• This is the fluid between the inner chloroplast membrane and the outside of thylakoids found in chloroplasts.

• The carbon fixation (Carbon-benson cycle) reactions occur here

Surface area to volume ratio

Cells with a greater BLANK have a more efficient exchange of materials with the environment.

Phospholipids

Located in the plasma membrane, these create a bilayer with their polar heads (phosphate group) and nonpolar tails (fatty acid). Therefore they are aphipathetic.

Peripheral Proteins

• These are loosely bound to the surface of membranes

• Hydrophilic with charged and polar side groups

Integral Proteins

• Span the membrane

• portions of BLANK found inside the membrane are hydrophobic, while those that are exposed to the cytoplasm or extracellular fluid tend to be hydrophilic.

• ex. Transmembrane proteins

Fluid Mosaic Model

• mosaic of proteins in a fluid bilayer of phospholipids

• not a static structure and is held together by hydrophobic interactions which are weaker then covalent bonds.

• Most lipids and some proteins can shift and flow along the surface of the membrane or across the bilayer.

Cholesterol

• Type of steroid

• Is randomly distributed and wedged bw phospholipids in the cell membrane of eukaryote cells

• regulates bilayer fluidity under different environmental conditions

Carbohydrates

• Diversity and location of BLANK and lipids enable them to act as markers

  • Glycoproteins = one or more BLANK attached to a membrane protein

  • Glycolipids = lipid with one or more BLANK attached

Channel Proteins

Hydrophilic tunnel spanning the membrane that allows specific target molecules to pass through

Carrier Protein

Spans the membrane and changes shape to move a target molecule from one side of the membrane to the other.

Cell Wall

• Functions as structural boundary:

  • protects and maintains shape of cell

  • prevents against cellular rupture when internal water pressure is high

  • helps plants stand up against forces of gravity

• Functions as a permeable barrier:

  • Plasmodesmata: small holes bw plant cells that allows the transfer of nutrients, waste and ions.

The BLANK is composed of complex carbs:

• in plants: cellulose

• In fungi: chitin

• In prokaryotes: peptidoglycan

Concentration Gradient

• a solute is more concentrated in one area than another

• A membrane separates 2 different concentrations of molecules

Passive Transport

• The net movement of molecules from high concentration to low without metabolic energy, such as ATP, needed

• Plays primary role in import of materials and export of waste

• Examples include Simple Diffusion and Facilitated Diffusion

Simple Diffusion

• Type of passive transport

• Small non-polar molecules pass freely (N2, O2, Co2, steroids)

• Small amount of H20 leak through the membrane

Facilitated Diffusion

• Type of passive transport

• Allows for hydrophilic molecules and ions to pass through membranes (H20, Na+, K+, Ca+)

Active Transport

• Requires direct input of energy (ex. ATP) to move molecules from regions of low concentration to high concentration

• Requires transport protein (like carrier proteins)

Endocytosis

• The cell uses energy to take in large particles (such as bacteria) and the uptake of fluids or macromolecules in small vesicles.

• Types:

  • Phagocytosis: cell takes in large particles (eating)

  • Pinocytosis: cell takes in extracellular fluid (drinking)

  • Receptor-Mediated Endocytosis: receptor proteins on the cell membrane are used to capture specific target molecules.

Exocytosis

• Internal vesicles use energy to fuse with the plasma membrane and secrete large macromolecules out of the cell.

  • Proteins like signaling proteins

  • hormones

  • waste

Hypertonic Solution

MORE solute

LESS solvent

GAINS water from hypotonic solution

Hypotonic

LESS solute

MORE solvent

LOSES water to hypertonic solution

Isotonic

EQUAL solute and solvent concentrations as the other solution.

EQUAL water movement into and out of the solution. (no net water movement.)

Tonicity

The measurement of relative concentration of solute bw 2 solution (inside and outside the cell)

Plant Cell Osmoregulatory Mechanisms

• this maintains water balance and allows control of internal solute composition / water potential

  • Environmental hypertonicity

    • plasmolysis

  • Isotonic solution

    • flaccid

  • Environmental Hypotonicity

    • turgid

Animal Cell Osmoregulatory Mechanisms

• This maintains water balance and allows control of internal solute composition / water potential

  • Environmental hypertonicity

    • shriveled

  • Isotonic solution

    • normal

  • Environmental Hypotonicity

    • Lysed