Bio 110 Exam 3

What structures are found in the nucleus?

chromosomes, long linear molecules of DNA that contain the genetic info

Where are proteins made

ribosomes

Where are ribosomes found

free in the cytoplasm or attached to the rough endoplasmic reticulum

What kind of covalent bonds are needed to make a protein?

amide bonds (peptide bonds while connecting amino acids)

What are ribosomes made out of?

RNA and protein

How are ribosomes constructed?

rRNA forms the core of the ribosom’es structure and is the actual catalytic molecule that speeds the formation of amide/peptide bonds in the protin

Which part of the ribosomes forms its core?

rRNA

Which part of the ribosome catalyzes the formation of peptide bonds in the protein?

rRNA

What is the order of events of protein synthesis?

mRNA transcribed in the nucleus, mRNA exits through nuclear pores, mRNA meets small subunit of the ribosome in the cytoplasm, the mRNA and small subunit, and the mRNA is translated into protein.

The sequence of amino acids in the protein is determined by the sequence of

nucleotides in the mRNA, which was copied from the sequence of the DNA

What are the subdivisions of the endomembrane system?

i. endoplasmic reticulum

ii. golgi complex

iii. membrane-bound vesicles

Membrane bound vesicles

transport materials between parts of the system

Functions of RER

synthesis of proteins destined for the membrane, for export (secretion), and for other organelles. proteins are synthesized by ribosomes on the RER, which segregates all of the protein or part of it inside the lumen of the RER after synthesis

Functions of SER

synthesize the membrane components phospholipid and cholesterol, and to detoxify foreign substances, much as drugs and toxins

How do Golgi and ER function together?

they are a system for synthesize proteins and lipids and directing them to their correct location of the cell. Protein and lipid material starts in the ER and moves to the cis face of the Golgi via transport vesicles

Golgi functions

further modifies proteins whose modification starts with the ER. Also sorts proteins by their eventual destination

Steps of the pathway for secreted proteins

RER, transport vesicles, sacs of the cis Golgi, sacs of the trans Golgi, secretory vesicle, and fuse with plasma membrane, releasing contents in a process called “exocytosis”

Endocytosis

process of bringing bulk materials into the cell

Exocytosis

the process of ejecting bulk materials from the cell

Different kinds of endocytosis

phagocytosis, pinocytosis

Phagocytosis

cell eating

Pinocytosis

cell drinking

Properties of Lysosomes

have an acidic pH and a set of digestive, hydrolytic enzymes. They function best at acidic pH

Primary lysosome

fuses with the endosomes to generate a secondary lysosome and digest the material inside

Lysosome involvement in endocytosis

used to digest the material brought into the cell by endocytosis, to render the material harmless and make the digested material usable to the cell

Structure of mitochondrial membranes

two membranes.

outer membrane covers the entire organelle

inner membrane is entirely folded

How did mitochondria arise as organelles

they were originally free-living bacteria that became incorporated into the cytoplasm of eukaryotic cells. They are self replicating

Chloroplasts were once

free-living bacteria

What organelles are unique to plants

plastids and vacuoles.

Most important plastid is the

chloroplast

Internal membrane structure of a chloroplast

three membranes,

outer membrane completely covers the organelle, inner membrane also completely covers the organelle. Chloroplasts have a third membrane

Chloroplasts have a third membrane, called the

thylakoid membrane is the site of photosynthesis

Different cytoskeletal elements

microfilaments, microtubules and intermediate filaments

Microfilaments

made of actin

long, thin fibers that support the cell, and in association with myosin, help the cell move

Microtubules

hollow tubes that also provide structural support, and help the cell move

responsible for moving objects, such as vesicles, around the cell.

form “railroad tracts” on which the motor proteins dynein and kinesis carry cargo one direction of dyenin and the other direction of myosin

Intermediate Filaments

composed of long strands made from fibrous protein subunits noncovalently bonded end to end

provide shape and structural support at various places in the cell

do NOT have role in movement

What kinds of proteins interact with cytoskeletal elements to create motion and movment?

motor proteins

Dynein and kinesin interact with

microtubules

Fibrous Connective Tissue

contains a large amount of extracellular matrix with relatively few cells

Example of Fibrous connective tissue

tendons and ligaments

Epithelial Cells

cells that form layers, often lining the internal cavities of the body, such as the intestines

separated from the rest of the body by a sheet of extracellular matrix called the basal lamina

Functions of Plasma Membrane

separates external from internal compartments

semipermeable barrier

has a very thin flexible covering

What makes the membrane a bilayer

the area of a monolayer of phospholipids from red blood cells is twice the area of the membrane in those cells

Phospholipids

consist of polar head groups and nonpolar fatty acid tails

in presence of water, they organize into bilayers

Membranes are selectively

permeable

A pure phospholipid membrane is somewhat permeable to

small polar molecules

A pure phospholipid membrane is very impermeable to

ions and other charged molecules

What is a model in science?

simpler description of a complex phenomenon

conceptual and analytic

What is the role of models in modern day science?

developing and testing them

what does it mean when a membrane is “fluid”

membrane maintains a barrier between what is inside and outside the cell

extends to proteins

Can the cell control the degree of fluidity in the membrane?

the chemical structure of fatty acids int eh membrane controls the degree of fluidity of the membrane

The cell can control the degree of fluidity by

changing the fatty acids of the phospholipids in the membrane

If the membrane has more unsaturated fatty acids, it will be

more fluid

if the membrane has more saturated fatty acids, then it will be

less fluid

Longer chain fatty acids will tend to make the membrane

less fluid

The shorter the chain fatty acids, will make the membrane

more fluid

How would a cell respond to an increase in temperature to maintain the same membrane fluidity?

the membrane would be more fluid, if too fluid, it will compensate to return the membrane to its original level of fluidity

cell would increase in the relative amount of saturated fatty acids and/or increase the length of the chains in the newly synthesized phospholipids, either of which decrease membrane fluidity

How would a cell respond to a decrease in temperature to maintain the same membrane fluidity?

less fluid membrane

if not fluid enough, will compensate

would increase the relative amount of unsaturated fatty acids and/or decrease the length of the chains in the newly synthesized phospholipids

If there is a higher concentration of a small hydrophobic molecule outside the cell than inside, what will happen?

the small hydrophobic molecule would enter the cell by simple diffusion

NO protein works with

intermediate filaments

anything that ends with “in” is a

protein

How can molecules that are permeable to the membrane move from a region of high concentration to a region of low concentration?

simple diffusion

what happens to molecules that are not permeable to the membrane?

facilitated diffusion

Facilitated diffusion proteins:

carrier proteins and channels

carrier protein

transports molecules one (or a few) at a time with each cycle of transport

channel proteins

allow many molecules to be transported at once

Facilitated diffusion and active transport can BOTH

transport molecules that are not permeable to a lipid bilayer across the membrane

A carrier must bind to a __________ _______ _______ before transport can occur

single molecule substrate

Channels allow the flow of molecules one after another through the channel is the analogy that they are like

bridges

Carriers for facilitated diffusion and transporters for active transport can both be classified into

uniporters, symporters, or antiporters

Uniporters

transport only a single molecular species in a single direction

Symporters and Antiporters

allow the transport of more than one species but differ in the directionallity of transport

Symporters carry

two species in the same direction

Antiporters carry two species in the

opposite direction

Osmosis

movement of water across a semipermeable barrier in response to a difference in concentration of solutes on either side of the membrane

When the solutes are impermeable to the membrane

water will follow the concentration gradient of free water, moving from regions of low solute concentration to high solute concentration

Isotonic Solutions

have the same concentration of solutes as a cell

cell is immersed in this solution, nothing will happen

Hypertonic Solution

greater concentration of solutes in a cell

water will move from inside the cell to outside causing it to shrivel and may die

Hypotonic Solution

those where the concentration of solutes is less than in a cell

if cell is placed in this solution, the concentration of solute is higher inside the cell. water will move into the cell and may cause it to BURST

parts of chromosome 1 that are being transcribed

are contained in the euchromatin

are contained in a different territory than chromosome 2

Germ line cells

eventually become sperm or egg

have to protect DNA for many generations

What molecule acts as a catalyst for formation peptide bonds?

ribosomal RNA (rRNA)