The Human Cell

Question 1

What is the Plasma Membrane

Answer 1

The membrane on the surface of animal cells
Made mainly of lipids and Protein
Function = regulate the movement of substances in and out of the cell
Contains receptor molecules which allow it to respond to chemical like hormones
Participates in the generation and conduction of electrical current

Question 2

What is the Nucleolus

Answer 2

Organelle within the nucleus and is responsible for Ribosonal RNA synthesis and ribosone production

Question 3

What are Nuclear Pores

Answer 3

• small channels spanning the nuclear membrane
• Lined by a set of protiens called nuclear pore complex
• Allow for passage of metabolites, macromolecules

Question 4

What is the Nucleus

Answer 4

Largest organelles of a cell
Surrounded by nuclear membrane
Contains Chromosomes (hereditary info)
Function = Controls cell activity and assembles ribosomes for protein manufacture

Question 5

What is the Cytoplasm

Answer 5

Gel like fluid inside the cell
Site of many cellular activities
Fluid part of the cytoplasm is called cytsol
Cytosol contains water, nutrients, enzymes and other substances

Question 6

What are Ribosomes

Answer 6

Organelles responsible for protein synthesis
Two types of ribosomes in a cell are free and fixed ribosomes
Free ribosomes - scattered throughout the cytoplasm create protein to be used within the cell
Fixed ribosomes - attach to Endoplasmic Reticulum where they are modified for use within the cell or secreted from the cell

Question 7

What is Endoplasmic Reticulum

Answer 7

• A sytem of membranes channels continues with the nuclear membrane extending throught the cytoplasm
• Contain internal spaces called Cisternae
• Responsible for the transportaion of production of molecules

Question 8

What is the smooth Endoplasmic reticulum

Answer 8

• Synthesizes lipids, phospholipid, carbohydrates (e.g. glycogen) and cholestural steroid hormones
• Absorbs and transports fats
• Detoxification of drugs (in liver and kidneys)
• SER in skeletal muscle stores Calcium ions

Question 9

What is Rough Endoplasmic Reticulum

Answer 9

• Folds and processes proteins that have been made at the ribsomes on its surface (fixed ribosomes).
• Many of these proteins are then modified and packaged for export to there next destination the Golgi apparatus

Question 10

What are Golgi Apparatus

Answer 10

• A group of Fluid filled membrane bound flattened sacs
• Modify and packages and distribute proteins and lipids
• Adds or removes carbohydrates to and from proteins to change their function
• Renews or modifies plasma membrane
• Makes Lysomes
• It has the ability to break off into vesicles and can thus facilitate the exocytosis of these modified products.

Question 11

What are Golgi Vesicles

Answer 11

• Small fluid filled sac surrounded by membrane
• Carry newly synthesized protein or glycoprotiens destined for export out of the cell

Question 12

What are Lysosomes

Answer 12

• Vesicles filled with digestive enzymes
• They can be used to digest invading cells or breakdown worn out components

Question 13

What main cellular function is performed by the mitochondria?

Answer 13

Mitochondria are involved in cellular metabolism, specifically the production of energy via aerobic respiration.

In the mitochondria, the Krebs cycle produces electron carriers, while the electron transport chain facilitates the formation of a proton gradient. This gradient is used to produce ATP.

Krebs cycle = Electron Carrier

Electron transport chain = Proton Gradient

Proton Gradient = used to produce ATP

Question 14

membrane

What are mitochondria

Answer 14

• Mitochondria large bean shaped organelles which provide energy for cells.
• Consist of an unusal double membrane, outer membrane covers the whole of the organelle and the inner membrane contains folds known as Cristae (increase surface area).
• Produce 95% of energy required by a cell in the form of AdenosineTriPhosphate ATP.
• Found in cells whcih requiee lots of energy (mucles, sperm)

Question 15

Which cell structures consists of DNA chains wrapped around histone proteins?

Answer 15

Chromatin

Question 16

What are peroxisomes

Answer 16

• Vesicles contatining degradeative enzymes
• Catabolize fats and other organic compounds

Question 17

Which component of the cell membrane is responsible for the membranes ability to form a barrier between a cells internal and external environment.

Answer 17

Phospholipid Bilayer enables the cell membrane to act as a selective physical barrier.

Question 18

Membrane proteins may function as what 5 answers

Answer 18

Receptors - extracellular materials bind to them and change cell activity

Channel - permit water, ions and solutes to bypass lipid membrane

Carrier - transport solutes across the cell membrane

Enzymes - Catalyze reactions in cell

Anchors - attach the cell membrane to other structures and stabalize it

Identifiers/recognisers - Identify a cell as normal, abnormal to the immune system

Question 19

Regarding membrane transport give three forms of passive procceses

Answer 19

Diffusion - net movement of molecules from an area of high concentration to an area of low concentration
Particles diffuse down the concentration gradient
Facilitated diffusion - Specialized protein carrier molecules attract and bind to substances too big to diffuse through semipermiable membrane. The carrier changes its shape and deposits the substance on the other side of the membrane.
Osmosis - Passive movement of water down the concentration gradient across a semipermiable membrane.

Question 20

What is passive transport

Answer 20

when substances can move across semipermiable mebranes down the concentration gradient without using energy

Question 21

What is Active Transport

Answer 21

Transprot of substances against the concentration gradient from a lower to a higher concentration.

Question 22

What is the Cytoskeleton

Answer 22

Internal protein framework of various filaments and tubles giving the cytoplasm strength and support.

Question 23

What are microfilaments what are they made from

Answer 23

• Tiny fibres made from actin
• Anchored to the cell membrane and provide support and shape
• Part of the cytoskeleton

Question 24

What are Microtubles

Answer 24

• Large rigid proteins
• Provide pathways for internall movement of organelles and chromosomes during cell division
• Part of the Cytoskeleton

Question 25

What are Cell extensions

Answer 25

These project form the plasma mebmrane in some cell types There main components are Microtubles

Question 26

What are Microvilli

Answer 26

* Tiny projections that cover the surface of some cells * They increase surface area of a cell * Common feature in cells actively engaged in absorbing materials from extracellular fluid e.g. digestive tract, Kidneys

Question 27

What are Cilia

Answer 27

* Tiny hair like projections that lie along the free border of some cells * They beat in unison moving substances along their surface * In the respritaroy tract mucus is moved by the ciliary action away from the lungs toward the mouth to be swallowed

Question 28

What are Flagella

Answer 28

* Single whip like projecvtions containing microtubles * They form the tail of Sdperm and are used fro locomotion to proppel sperm through the female reproductive tract

Question 29

What is Bulk Transport

Answer 29

* Is the transport of particals too large to cross a cell membrane * This is done by Endocytosis (moving molecules into a cell by enclosing them in a vesicle made out of plasma membrane) * Pinocytosis allows the cell to bring in fluid * Phaygocytosis is where the particel is engulfed, vacuole formed and lysosomes fuse with vacuole releasing enzymes that digest the contents * Exocytosis is then used to expell the waste material from inside the cell outside using vesicles that fuse to the plasma membrane

Question 30

# centrisome-centrioles-microtubles What are Centrosome/Centrioles and their function

Answer 30

* Centrosomes organize microtubles in a cell * Consist of two centrioles made from microtubles * Responsible for the formation of the mitotic spindle during mitosis which is needed for the movement of chromosomes

Question 31

Describe in detail the phospholipid bi layer

Answer 31

* Part of the plasma membrane * Two layer of phosoplipids * They have a head (phosphate) and a tail fatty acid tail (lipid) * Head is charged do to the presence of a phosphate molecule (Hydrophilic) soluble in water and faces externally (likes water) * Tail insoluble in water (Hydrophobic lipid body) project internally between the heads dosent like water * Also contains cholestural which provid fluidity to the membrane * Allows lipid soluble molecules to pass but doesnt allow ions and water soluble components to enter. * This is what makes the plasam membrane selectivley permiable

Question 32

In terms of membrane proteins how do they function as channels

Answer 32

permit water ions and solutes to bypass lipid membrane

Question 33

In terms of membrane proteins how do they act as receptors

Answer 33

Extracellular materials bind to receptors in the membrane and change cell activity

Question 34

In terms of membrane proteins how do they act as carriers

Answer 34

They transport solutes across the cell membrane

Question 35

In terms of membrane proteins how do they function as enzymes

Answer 35

Catalyze reactions in the cell

Question 36

In terms of membrane proteins how do they function as anchors

Answer 36

They attach the cell membrane to other structures and help stabalize it

Question 37

In terms of membrane proteins how do they function as Identify/recognisers

Answer 37

They identify a cell as normal or abnormal. Helps to recognize cells that may be causing infection

Question 38

what are protosomes

Answer 38

Break down and recycle damaged or abnormal protiens in a cell Cylindrical sturcuture containing Protease Protease is a protein breaking enzyme

Question 39

label the cell

Answer 39

Question 40

Explain the fluid mosaic model

Answer 40

The fluid mosaic model is used to describe the plasma membrane. It is composed of lipids with a “mosaic” of embedded proteins and other components, and its “fluidity” allows these macromolecule components to move laterally within the membrane.

Question 41

Which human cells do not contain a nucleous

Answer 41

Erythrocytes Red Blood cells

Question 42

Give four molecules that are permiable to the phospholipid bilayer

Answer 42

Small molecules Oxygen Carbon dioxide Water Lipid soluable steroids