Lecture 1 - Cells And Membranes

Question 1

Differences between prokaryotes and Eukaryotes

Answer 1

Prokaryotes- small, simple cell structure , lack internal membrane bound organelles

Eukaryotes- bigger, more complex cell structure, internal membrane bound organnels, nucleus

Question 2

Examples of prokaryotes

Answer 2

Bacteria and archaebacteria

Question 3

Examples of Eukaryotes

Answer 3

Fungi, Protozoa, animals and plants

Question 4

Structure of a Prokaryotes (bacteria)

Answer 4

Cytoplasm , Cell wall , plasma membrane and DNA

Question 5

What’s different about a prokaryotes DNA?

Answer 5

It’s circular in a Nucleoid

Question 6

What is the role of the Cytoplasm and the Plasma membrane in the Prokayote?

Answer 6

Cytoplasm- contains ribosomes for protein synthesis

Plasma memebrane- reactions occur

Question 7

Structure of Eukaryotes

Answer 7

Internal membrane bound organelles
True nucleus bounded by double membrane
DNA organised into linear chromosomes
Compartmentalisation so organelles can carry out different functions

Question 8

All multicellular organisms are Eukaryotes, cells are …………..

Answer 8

Differentiated depending on their function

Question 9

Plants fungi and many protists have cells surrounded by a

Answer 9

CELL WALL

Question 10

What does a cell wall do?

Answer 10

Maintains cell shape

Prevents excessive water uptake

Question 11

Animals cells lack….

Answer 11

A cell wall

Question 12

What surrounds an animal cell?

Answer 12

Extracelluar matrix

Question 13

What makes up the Extracelluar matrix

Answer 13

Collagen , elastin, fibronectin, laminin and gylcosaminoglycans form a protective layer over the cell surface

Question 14

ECM is attatched to the plasma membrane by

Answer 14

Glycoprotein fibronectin

Question 15

How does Fibronectins work?

Answer 15

Bind the ECM to proteins called intertgins which are imbedded in the plasma membrane

Question 16

How large are prokaryotes compared to Eukaroyrotes

Answer 16

1-10um

5-100um

Question 17

Cells are small so more can be packed into one space and there’s more surface area

Answer 17

Multicelluarity

Question 18

Further detail on the Structure of a Eukaryotic cell

Answer 18

Centrioles
Chloroplasts
Er smooth
Er rough
Golgi apparatus
Lysosomes
Mitochondria
Nucleus

Question 19

What’s cytosol and what’s it’s main component?

Answer 19

The matrix inside the cell membrane

Water

Question 20

What’s a Cytoskeleton and what’s it important for?

Answer 20

It’s a Network of 3 types of proteins

• microtubules
• intermediate filaments
• Actin filaments

Important for sturcturen and internal transport

Question 21

What are microtubules?

Answer 21

Long hollow cylindrical structures with dynamic instability

Question 22

Intermediate filaments

Answer 22

Intermediate in side

Form twisted ropelike structure

Question 23

Actin filaments

Answer 23

Long thin fibres

Question 24

What is the nucleus and the endomembrane system?

Answer 24

• Network of membranes enclosing the nucleus, ER, Golgi and lysosomes
• also includes plasma membrane
• connected directly to eachother or pass materials via vesicles

Question 25

Nuclear Envelope

Answer 25

Double membrane structure enclosing nucleus Outer membrane of the nuclear envelope it continuous with the ER membrane Nuclear pores provide passageways Materials within are not part of the endomembrane system

Question 26

Features of the nucleus

Answer 26

Chromosomes •Nuclear matrix- filamentous network that organises * chromosomes * Ribosome assembly- occurs in the Nucleus

Question 27

Features of endoplasmic rectilium

Answer 27

* Network of membranes that form flattered fluid tubules or cisternae * ER membrane encloses a single compartment called the ER lumen * RER studded with ribosomes and involved in protein synthesis and sorting * SER lack ribosomes and does DETOXIFICATION,CARBOHYDRATE METABOLISM, CALCIUM BALANCE, SYNTHESIS AND MODIFICATION OF LIPIDS

Question 28

Golgi apparatus

Answer 28

* Stacks of flattened membrane bounded compartments * Vescicles transport materials between stacks * Secretion, processing and protein sorting

Question 29

Lysosomes

Answer 29

Contain acid hydrolysed that perform hydrolysis Many different types of acid hydrolysed to break down proteins , carbohydrates, nucleiic acids and lipids Autophagy- recycling of worn out organelles through endocytosis

Question 30

Peroxisomes

Answer 30

* catalyse certain reactions that break down molecules by removing hydrogen or adding oxygen * hydrogen peroxide is a byproduct * catalase breaks down dangerous h202 into water and oxygen

Question 31

Mitochondria

Answer 31

* Makes atp * Outer and inner membrane * Also involved in synthesis modification and breakdown of several types of cellular molecules * Contain their own DNA, divide by binary fission

Question 32

Plasma membrane

Answer 32

* Boundary between the cell and the Extracellular environment * Functions - Membrane transport , selective permeability - Cell Signalling , using receptors - Cell adhesion

Question 33

8 important functions of cellular membranes

Answer 33

1. Cell compartmentalisation 2. Cell and Nucluear Division 3. Selective uptake and export or ions or molecules 4. Protein sorting 5. Anchoring of the cytoskeleton 6. Production of energy intermediates such as ATP 7. cell signalling Adhesion of molecules to eachother and to the Extracellular matrix

Question 34

Functions of membrane proteins

Answer 34

* transporters * enzymes * cell surface identity markers * cell adhesion proteins * attatchment to cytoskeleton

Question 35

2 types of membrane proteins

Answer 35

Integral and peripheral (extrinsic)

Question 36

Integral membrane proteins 2 types

Answer 36

1. Transmembrane - atleast one membrane spanning region of the protein 2. Lipid anchor protein - protein covaelently attatched to lipid

Question 37

Peripheral proteins

Answer 37

* don't interact with hydrophobic interior | * bond by hydrogen bonds or ionic bonds to the regions of integral proteins that project out from the membrane

Question 38

Type of transport across membrane - Passive Transport

Answer 38

•diffusion - random motion causes a net movement of substances from a region of high concentration to low concentration

Question 39

Facilitated diffusion- 3 points

Answer 39

* transports ions and other solutes * facilitate movement by physically binding molecules on one side of the membrane and releasing them on the other * essential characterises- specific, passive, saturates

Question 40

Active Transport

Answer 40

Expenditure of energy to move substances against their concentration gradient * involves highly selective protein carriers * sodium potassium pump * uses ato

Question 41

Sodium Potassium pump 6 steps

Answer 41

1. Protein in membrane binds to intracelluar sodium 2. ATP phosphorylates protein with bound sodium 3. phosphorylation causes conformational change in protein, allowing sodium to leave 4. Extracelluar Potassium binds to exposed sites 5. Binding of Potassium causes dephosporalisation of protein 6. Dephosphorlyisation changes protein shape back to original and cycle repeats

Question 42

Coupled transport

Answer 42

Some molecules are moved up their concentration gradient by using the energy stored in the gradient of a different molecule