bio 2 test

All organisms are made of

cells

The ______ is the simplest collection of matter that can be alive

cell

How are all cells related

By their descent from earlier cells

How do Prokaryotic and Eukaryotic cells differ

their internal membranes

Some __and _____ are common to both types of cells

organelles, functions

Organelles with their own membranes are specific to \n

Eukaryotic cells

Plasma membrane

a selective barrier that allows sufficient passage of oxygen, \n nutrients, and waste to service the volume of every cell

The plasma membrane is made primarily from which macromolecule?

Lipids

The general structure of a biological membrane is a

double layer of phospholipids

The basic structural and functional unit of every \n organism is one of two types of cells:

prokaryotic or eukaryotic

Only organisms of the domains Bacteria and Archaea consist of

prokaryotic cells

Protists, fungi, animals, and plants all consist of

eukaryotic cells

Basic features of all cells:

– Plasma membrane \n – Semifluid substance called cytosol (cytoplasm) \n – Chromosomes (carry genes) \n – Ribosomes (make proteins)

Things specific to Prokaryotic Cells

– No nucleus (DNA in an unbound region called the nucleoid) \n – No membrane-bound organelles

Eukaryotic cells are characterized by having:

– DNA in a nucleus that is bounded by a \n membranous nuclear envelope \n - Membrane-bound organelles

\-They are also much larger than prokaryotic cells

Which cellular structure is common to both prokaryotic and eukaryotic cells?

\n Plasma membrane surrounding the cell

Cell fractionation

takes cells apart and separates the major organelles from one another

How does cell fractionation work?

Centrifuges fractionate cells into their component parts

What is the point of cell fractionation?

Cell fractionation enables scientists to determine \n the functions of organelles

_______ and _________ help correlate cell function with structure

Biochemistry, cytology

You have a solution containing all four of the components \n listed above. If you centrifuge (spin) that solution at a speed \n just fast enough to bring viruses into the pellet, what else \n would you definitely find in the pellet along with viruses?

Mitochondria

What is the correct order of the exocytosis or secretion pathway?

rough ER, vesicle, Golgi apparatus, vesicle, plasma \n membrane

How are the mitochondria and chloroplasts similar to bacteria?

* Enveloped by a double membrane
* Contain free ribosomes and circular DNA \n molecules
* Grow and reproduce somewhat independently \n in cells

Endosymbiont theory

\n

A symbiotic relationship where one organism lives inside is known as endosymbiosis.

Mitochondria have a smooth outer membrane \n and an inner membrane folded into

cristae

The inner membrane of the mitochondria creates two compartments:

inter membrane space and mitochondrial matrix

What does chloroplast contain?

They contain chlorophyll and enzymes and other molecules that function in photosynthesis

Where is chloroplast found?

They are found in leaves and other green organs of plants and in algae

Chloroplast structure includes;

Thylakoids and Stroma

What is thylakoids?

membranous sacs, stacked to \n form a granum

What is stroma?

the internal space

Which of the following is not the name of a membrane-bound compartment in a eukaryotic cell?

ribosomes

What is the plasma membrane?

It is a fluid boundary composed of a combination of lipids and proteins that separates the living cell from its surroundings

All membranes have two distinct ____ which have \n different

sides, functions

How do molecules pass through membranes?

* Membranes are selectively permeable
* Membrane proteins aid in movement of some molecules

Concentration gradients define:

the direction of molecular movement and/or the energy requirements of molecular movement

____ cargo cannot pass through the membrane and \n must enter/leave the cell by other means

Very large

Which lipids are the most abundant lipid in the \n plasma membrane?

Phospholipids

Amphipathic molecules

molecules that contain hydrophobic and hydrophilic regions

The fluid mosaic model states that

a membrane is a fluid structure with a “mosaic” of various proteins embedded in it

____ and _____ in the plasma membrane can move within the bilayer

Phospholipids, proteins

Based on what we have just discussed about membrane fluidity, what would you predict about the outcome of the experiment outlined above?

Mouse and human proteins will mix in the membrane \n quickly

A lipid bilayer in a human cell made of which of the following lipids would be the most fluid?

Phospholipids with unsaturated fatty acids

What is a membrane?

a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer

What determines most of the membrane’s specific functions?

Proteins

Which proteins are bound to the surface of the membrane

Peripheral proteins

Which proteins penetrate the hydrophobic core?

\n Integral proteins

What are transmembrane proteins?

Integral proteins that span the membrane

In order for a protein to be an integral membrane protein \n (transmembrane protein) it would have to be...

amphipathic, with at least one hydrophobic region.

The hydrophobic regions of a Transmembrane protein consist of one or more stretches of

non-polar amino acids, often coiled into alpha helices

What kind of molecules can dissolve in the lipid bilayer and pass through the membrane rapidly?

Hydrophobic (non-polar) like hydrocarbons

Which molecules have trouble crossing the membrane?

Large polar molecules, like sugars

Which molecules can pass through the membrane slowly?

Small polar molecules

Diffusion

the tendency for molecules to spread out evenly into the available space

Although each molecule moves randomly, diffusion \n of a population of molecules may be

directional

What does it mean for molecules to be at a dynamic equilibrium

as many molecules cross the membrane in one direction as in the other

Concentration gradient

the region along which the density of a chemical substance increases or decreases

How much work must be done to move substances down the concentration gradient?

No work

What kind of transport is the diffusion of a substance across a biological membrane?

Passive transport because no energy is being expended

Facilitated diffusion

transport proteins speed the passive movement of molecules across the plasma membrane

What are the role of channel proteins?

they provide corridors that allow a specific molecule or ion to cross the membrane

Channel proteins consist of

Aquaporins and ion channels

What do aquaporins do?

They control the passage of water molecules across a cell membrane.

What do ion channels do?

they open or close in response to a stimulus (gated channels)

Carrier Proteins

They bind specific solutes and transfer them across the lipid bilayer. Passive transport

Osmosis

the diffusion of water across a selectively permeable membrane

In osmosis, water diffuses across a membrane from the \n region of ____ solute concentration to the region of _____ solute concentration until the solute concentration is equal on both sides

lower, higher

Tonicity

the ratio of solute concentration inside the cell vs. outside the cell

Isotonic solution

Solute concentration is the same as that inside the cell; no net water movement across the plasma membrane

Hypertonic solution

Solute concentration is greater than that inside the cell; cell loses water

Hypotonic solution

Solute concentration is less than that inside the cell; cell gains water

What happens to a cell when placed in a hypotonic solution?

Net movement of water into the cell increases

What happens to a plant cell when placed in a hypotonic solution?

It becomes rigid due to increased interior pressure

what is the role of cell walls?

They help maintain water balance

What happens if a plant cell and its surroundings are isotonic?

there is no net movement of water into the cell and the cell becomes flaccid (limp), and the plant may wilt

What happens to a plant in a hypertonic environment?

plant cells lose water; eventually, the membrane pulls away from the wall, a usually lethal effect called \n plasmolysis

Plasmolysis

The process of contraction or shrinkage of the protoplasm of a plant cell and is caused due to the loss of water in the cell.

Why is facilitated diffusion still passive?

The solute moves down its concentration gradient, and the transport requires no energy

How can some transport proteins move solutes against their concentration gradients?

They require energy

Active transport

moves substances against their concentration gradients with the use of energy

What type of energy does active transport usually use?

ATP

Active transport is performed by

specific proteins embedded in the membranes

\n Active transport allows cells to maintain concentration gradients that _____ from their surroundings

differ

Sodium-potassium pump

At type of active transport; moves sodium and potassium ions against large concentration gradients

The sodium-potassium pump in animal cells requires cytoplasmic ATP to pump ions across the plasma membrane. When the proteins of the pump are first \n synthesized in the rough ER, what side of the ER membrane will the ATP binding site be on?

It will be on the side facing the interior of the ER.

Membrane potential

the voltage difference across a membrane

How is voltage created?

by differences in the distribution of positive and negative ions across a membrane

What is an electrogenic pump?

a transport protein that generates voltage across a membrane

When does cotransport occur?

occurs when active transport of a solute indirectly drives transport of other solutes

What kind of transport does cotransport involve?

active transport coupled with a form of passive transport

What is bulk transport?

Across the plasma membrane occurs by exocytosis and \n endocytosis

What is exocytosis?

Transport vesicles migrate to the membrane, fuse with it, and release their contents

What is endocytosis?

the cell takes in macromolecules by forming vesicles from the plasma membrane

\n Bulk transport _______ requires energy

does

What is phagocytosis?

a cell engulfs a particle in a vacuole and then the vacuole fuses with a lysosome to digest this particle

Water passes quickly through cell membranes because:

specialized proteins form hydrophilic channels.

What is metabolism?

the totality of an organism’s chemical reactions

What is a metabolic pathway?

It begins with a specific molecule and ends with a product and each step is catalyzed by a specific enzyme

Catabolic pathways

release energy by breaking down complex molecules into simpler compounds

What are some examples of catabolic pathways?

Cellular respiration and hydrolysis