AP Biology Unit 2

Ribosomes comprise

RNA and Protein

Ribosomes synthesize

protein according to mRNA sequence

Ribosomes are found in

All forms of life, reflecting the common ancestry of all known life

The endomembrane system consists of

a group of membrane-bound organelles and sub cellular components that work together to modify, package, and transport polysaccharides, lipids and proteins intracellurlarly

Organelles in the endomembrane system include

the endoplasmic reticululum, Golgi complex, lysosomes, vacules, transport vesicles, the nuclear envelope, and plasma membrane.

Endoplasmic reticulum provides

mechanical support by helping cells maintain shape and plays a role in intracellular transport.

The Rough ER is associated with

membrane bound ribosomes, which allows for the compartmentalization of cells, and helps carry out protein synthesis

The Smooth ER functions include

the detoxification of cells and lipid synthesis

The Golgi complex is a membrane-bound structure that consists of a

series of flattened membrane sacs

Functions of the Golgi include

the correct folding and chemical modification of newly synthesized proteins and packaging proteins for trafficking

Mitochondria have a _________ Membrane that provides

-double

compartments for different metabolic reactions involved in aerobic cellular respiration.

The Mitochondria's outer membrane is ________ while the inner is __________, forming

-smooth -highly convoluted

folds that enable ATP to be synthesized more efficiently.

Lysosomes are

membrane-bound sacs that contain hydrolytic enzymes that digest material.

Lysosomes play a role in

programmed cell death (apoptosis)

Catalysis

Hydrolytic enzymes act as catalysts, increasing the rate of a reaction without being consumed in the process

Hydrolysis

The function by facilitating a process called hydrolysis, where a water molecule is used to cleave a specific chemical bond within a larger molecule

Molecular Breakdown

This action breaks down complex macro-molecules (like proteins, fats, and carbohydrates) into smaller, simpler units (such as amino acids, fatty acids, and sugars) that can be utilized by the organism

occurs mainly in the lysosomes and mitochondria

What is a vacuole?

A membrane-bound sac.

What is the function of a large vacuole in plant cells?

It maintains turgor pressure through nutrient and water storage.

How do vacuoles in animal cells differ from those in plant cells?

They are smaller in size, more plentiful, and store cellular materials and waste.

Chloroplasts are

specialized organelles that are found in plants and photosynthetic algae.

Chloroplasts contain

a double membrane and serve as the location for photosynthesis.

Surface to area volume ratios affect

the ability of a biological system to obtain necessary resources, eliminate waste products, acquire or dissipate thermal energy, and otherwise exchange chemicals and energy with the environment

The surface area of the plasma membrane must be

large enough to adequately exchange materials

The surface area-to-volume ratio can restrict

cell size and shape.

Smaller cells typically have a

higher surface area-to-volume ratio as well as more efficient exchange of materials with the environment than larger cells

As cells increase in volume, the surface area-to-volume ratio

decreases and the demand for internal resources increases

More complex cellular structures (e.g. membrane folds) are necessary to

adequately exchange materials with the environment.

As organisms increase in size, their surface area-to-volume ratio ____________ affecting

-decreases

properties like rate of heat exchange with the environment.

Smaller amounts of mass exchange proportionally

more heat with the ambient environment than do larger masses

As mass increases, both surface area-to-volume ratio and the rate of heat exchange _______________

decreases

in relation between metabolic rate per unit body mass and the size of multicellular organisms; typically the __________ the organism, the ________ the metabolic rate per unit body mass.

-smaller

-higher

phospholipids have both ____________ and _______________ regions

-hydrophilic -hydrophobic

The hydrophilic phosphate regions of the phospholipids are oriented

towards the aqueous external or internal environment

The hydrophobic phosphate regions of the phospholipids are oriented

facing each other within the interior of the membrane.

hydrophilic proteins are

charged and polar

hydrophobic proteins are

nonpolar

hydrophilic regions of the proteins are either

inside the interior of the protein or exposed to the cytosol (cytoplasm)

Hydrophobic regions of proteins make up the

protein surface that interacts with the fatty acids in the interior membrane

What is the structural framework of plasma membranes made of?

Phospholipid molecules

What types of molecules are embedded in plasma membranes?

Proteins and glycolipids

What model illustrates the movement of molecules within the plasma membrane?

Fluid mosaic model

The cell membrane is

selectively permeable determined by structure

Cell membranes separate the __________ environment of the cell from the ___________ environment

-internal

-external

Selective permeability is the result of the

plasma membrane having a hydrophobic interior

Small non-polar molecules, including __ , __ , and ___ freely pass across the membrane

N2, O2, and CO2

Hydrophilic substances such as large polar molecules and ions move across the membrane through

embedded channels and transport proteins

the non-polar hydrocarbon tails of phospholipids prevent

the movement of ions and polar molecules across the membrane.

Small polar uncharged molecules like H2O or NH3 pass through

the membrane in small amounts

cell walls of bacteria , Archaea, Fungi, and plants provide a ________________________ as well as a ___________________ for some substances to the internal or external cellular environments and protection from osmotic lysis.

-structural boundary

-permeability barrier

Cell walls of plants, prokaryotes, and fungi are composed of

complex carbohydrates

Passive transport is

the net movement of molecules from high to low concentration without ATP

passive transport plays a primary role in the

the import of materials and the export of wastes

Active transport requires

ATP in order to move molecules from low to high concentration

Selective permeable membranes allow for the formation of

concentration gradients of solutes across the membrane

process of endocytosis and exocytosis require energy to move

large substances or large amounts of substances into and out of cells.

in endocytosis, the cell takes in large molecules and particulate matter by

folding the plasma membrane in on itself and forming new (small) vesicles that engulf material from its external environment.

In exocytosis

internal vesicles release material from the external environment.

Membrane proteins are required for

facilitated diffusion of charged and large polar molecules through a membrane.

What is an example of facilitated diffusion involving water?

Large quantities of water passing through aquaporins.

Which charged ions require proteins to move through the membrane?

Na+ and K+.

What can happen to membranes due to the movement of ions?

Membranes may become polarized.

Facillitated diffusion enables the movement of

large polar molecules through membranes with no energy input.

In facilitated diffusion substances move

down the concentration gradient

Aquaporins

transport large quantities of water across membranes

osmosis

passive transport where water moves across the semi-pereable membrane from an area of high water concentration to low water concentration (high solute to low solute)

Water potential equation

Ψ = Ψs + Ψp

Ψp

pressure potential

Ψs

solute potential

Growth and homeostasis are maintained by the

constant movement of molecules across membranes

Osmoregulation

maintains water balance, and allows organisms to control their internal solute composition and water potential

Water moves from

regions of lows osmolarity or solute concentration to high osmolarity or solute concentration.

Solute potential of a solution equation

Ψs = −iCRT

i

ionization constant

almost always negative

C

Molar concentration

R

pressure constant R= 0.0831

T

temperature in kelvin (C+273)

Metabolic energy is required for

active transport of molecules and ions across the membrane to establish and maintain electrochemical gradients

Membrane proteins are necessary for

active transport

The Na+ + /K pump and ATPase contribute to

the maintenance of the membrane potential

Membranes and membrane bound organelles in eukaryotic cells compartmentalize

intracellular metabolic processes and specific enzymatic reactions

Internal membranes facilitate

cellular processes by minimizing competing interactions and by increasing surface area where reactions can occur

Membrane bound organelles evolved from

once free-living prokaryotic cells via endosymbiosis

Prokaryotes generally lack

internal membrane bound organelles but have regions with specialized structures and functions.

Eukaryotic cells maintain

internal membranes that partition the cell into specialized regions

mitochondria and chloroplast have their own

DNA seperate from the nucleus

Hypertonic

higher solute outside of the cell than water molecules so water molecules from inside the cells will leave to go into the solution

plasmolysis

shrinkage of the cell due to water molecules leaving the cell

Hypotonic

lower solute outside of the cell than water molecules so water molecules will go into the cell

cytolosis

bursting of cells caused by movement of water molecules into the cell

isotonic

equal solute and water outside the cell

Dynamic equilibrium

Amphiphilic

having a non-polar and polar

polar head is

hydrophilic (loves water)

non-polar tail is

hydrophobic (do not like water)

integral proteins

go through membrane

peripheral protein

sit on membrane

lysosomes need

low pH (acidic) for their enzymes to function