Biology 1001 Chapter 4

organelles, cells

Prokaryotic Cell

•Bacteria and Archaea

•No nucleus

•DNA in unbound region called the nucleoid region

•No membrane-bound organelles

What is inside the plasma membrane as a prokaryote?

•Cytoplasm: region of the cell that is contained within the plasma membrane

•Nucleoid region: location of DNA

•Ribosomes: protein synthesizers

Eukaryotic cells

•Compartmentalized by internal membranes

•Organelles

•Each organelle has a unique structure and function

•DNA housed inside membrane-bound nucleus

•Fungi, protists, plants, and animals all have eukaryotic cells

Proteome

When cells within the same organism (same genome) can have very different morphologies and functions

Cytosol

•Inside plasma membrane BUT region of eukaryotic cells that is outside organelles

Cytoplasm

•Everything inside the plasma membrane, including cytosol

Eukaryotic organelles

•Semiautonomous organelles

•Mitochondria and chloroplasts

•Nucleus

•Ribosome

•Endoplasmic reticulum

•Rough vs smooth

•Golgi apparatus

•Lysosomes

•Vacuoles

•Peroxisomes

The cell is a….

PROTEIN FACTORY!

Semiautonomous organelles

•Contain own DNA

•Grow and divide to reproduce themselves

•Depend on the cell for synthesis of internal components

(mitochondria and chloroplast)

Mitochondrial Function

•Cellular Respiration: In the presence of oxygen it can convert organic macromolecules (mostly sugars) into Energy for the cell (ATP).

Chloroplast Function

•Photosynthesis: Harness light energy

•Uses water and carbon dioxide to produce glucose and oxygen.

Nucleus

•Enclosed by the nuclear envelope

•Nuclear pores regulate entry and exit of molecules

•Functions:

•Protection, organization, replication

•Expression of genetic material

•Assembly of ribosomal subunits

Ribosome

•Involved in protein production by assembling Amino Acids into polypeptides.

•Smallest organelles

•2 types

•Free: in the cytosol

•Bound: attached to E.R.

Endoplasmic Reticulum (ER)

•Structure

•Cisternae:

•Flattened, fluid-filled tubules made from a network of membranes

•2 types of ER (they are continuous):

•Rough ER

•Smooth ER

Rough ER

•Studded with ribosomes •Functions: •Sorting and fold proeins into tertiary structure •Synthesizing proteins •Glycosylating proteins and lipids •Attachment of carbohydrates to proteins and lipids

Smooth Er

•Little to no ribosomes

•Functions in diverse metabolic processes:

•Carbohydrate metabolism

•Synthesis and modification of lipids

•Accumulation Ca²⁺

•Detoxifies drugs and poisons

Components of phospholipid bilayer

phospholipds

proteins

carboydrates

Leaflets

What is phospholipid bilayer is divided by

Leaflets

Half of a phospholipid bilayer

Asymmetrial —> extracellular, intracellular

What determines the fluidity of the membrane?

Lipid composition:

• length of phospholipid tails

• double bonds on phospholipid tails

• cholesterol (animal cells)

Optimal bilayer fluidity is essential for a cell because…

function, growth, and division

Two types of integral proteins

Transmembrane proteins

Lipid-anchored proteins

Definition of an integral protein

Penetrate the hydrophobic interior of the lipid bilayer

Transmembrane proteins

• span the membrane

• hydrophobic and hydrophilic regions

Lipid anchored proteins

• contain an amino acid that is covalently attached to a lipid

Peripheral proteins

• loosely associated with membrane surface

Selective Permeability

• allowing passage of some ions and molecules

• allows cells to maintain favorable internal environment

Golgi Apparatus

•Stack of flattened, membrane bound compartments

•Cis

•Medial

•Trans

Functions:

Directs the processing of molecules from the ER

Protein “assemble, package and sort”

Quality control of protein-modification

Secretion of cellular molecules

Lysosomes

•Involved in intracellular digestion of macromolecules and pathogens

•Contain: acid hydrolases

•Break down polymeric molecules into monomers

•Requires water

•Function optimally at acidic pH

Vacuoles

•Function: storage, regulation of cell volume, and degradation

•Plants have one large central _____

Peroxisomes

•Single membrane, fluid-filled lumen

•Functions:

•Breakdown organic molecules

•Catalyze detoxifying reactions

What cell are lysosomes found in?

•Animal cells only

What cells are peroxisomes?

All eukaryotic cells

Endomembrane system is a network of membranes including

Nuclear envelope

•Endoplasmic reticulum

•Golgi apparatus

Lysosomes

Vacuoles

Plasma membrane

Nuclear Envelope

•Encloses nucleus

•Double membrane

•Outer membrane continuous with ER membrane

•Nuclear pores: regulates entry and exit of molecules

Endomembrane system/Major Function?

•Protein sorting/exportation

What are the two types of ribosome?

•Free: in the cytosol (creates cytosolic protein)

•Bound: attached to E.R. (creates protein that enters the endomembrane system)

What is a peroxisomes

•Use catalase to break down hydrogen peroxide     H₂O and O₂

How does each protein reach its appropriate final destination

Protein Sorting

What are the three sorting signals?

•No signal

•Cotranslational sorting

•Post-translational sorting

No signal

Cytoplasm

Cotranslational Sorting

ER

Golgi

Lysosomes

Vacuoles

Plasma membrane

Secretion

Post translational

Nucleus

Mitochondrion

Chloroplast

Peroxisome

What 3 qualities do semiautonomous organelles have?

•Contain own DNA

•Depend on the cell for synthesis of internal components

•Grow and divide to reproduce themselves

Mitochondrion

•Plural: mitochondria

•Outer and inner membranes

•Inner membrane

•Highly folded

•Cristae

•Mitochondrial matrix

•Outer membrane

Chloroplast

•Carry out photosynthesis

•Structure

•Membranes:

•Inner membrane

•Outer membrane

•Thylakoid membrane

Functions of Smooth ER

-carbohydrate metabolism

-synthesis and modification of lipids

-accumulation of ca2+

-detoxifies drugs and posions

Functions of Rough ER

-sorting and folding proteins into tertiary structure

-synthesisizing proteins

-glycosating protiens and lipids (attachment of carbohydrates)

Functions of golgi apparatus

Directs the processing of molecules from the ER

Protein “assemble, package and sort”

Quality control of protein-modification

Secretion of cellular molecules

What are the four factors that affect ability of solute to pass through the membrane

• size

• polarity

• charge

• concentration

3 general ways to move across membranes

• simple diffusion

• facilitated diffusion

• active transport

Passive transport includes

Simple and Facilitated diffusion

Simple diffusion

• higher concentration to lower concentration

• passive transport —> no energy required

What is passive transport

• does not require energy

• molecules more down their concentration gradient: higher concentration not lower concentration

Osmosis

net diffusion of free water across a membrane

What type of transport is osmosis

PASSIVE

Define tonicity

ability of a surrounding of solution to cause a cell to gain or lose free water

3 types of tonicity

isotonic, hypertonic, hypotonic

isotonic

solutie equal on both sides of the plasma membrane

hypertonic

higher solute concentration

hypotonic

lower solute concentration

Active transport

• requires input of energy

• moving lower concentration to higher