week 1

Question 1

what are the properties of the main molecules of life?

Answer 1

• Amino Acids polymerise into Proteins
• Purines and Pyrimidines polymerise into Polynucleotides
• Polynucleotides can directly guide the formation of exact copies of their own sequence (base pairing of DNA)

Question 2

what did early earth consist of?

Answer 2

• Molten Surface?
• Atmosphere ammonia or methane?
• Little free Oxygen
• No Ozone
• Generally agreed –violent conditions, volcanic eruptions, lightning, storms….
• Great conditions for producing simple carbon-based (organic) molecules

Question 3

what happens if you mix gases sucg as CO2, CH3, NH3 and Hydrogen in water?

Answer 3

they react to form small organic molecules Purines, Pyrimidines,Sugars, Amino Acids

Question 4

what is the function of a plasma membrane?

Answer 4

• Every cell is surrounded by a plasma membrane
• Maintain homeostasis
• Selectively permeable
• Important in communicating without side environment
• Aids in binding and adhering

Question 5

what does cell theory state?

Answer 5

– Cells are the fundamental units of life.

– All organisms are composed of cells.

– All cells come from pre-existing cells.

Question 6

who was Robert Hooke and what did he discover?

Answer 6

The cell was first described by Robert Hooke

He remarked that they looked strangely similar to cellula or small rooms whichmonks inhabited, thus deriving the name.

However what Hooke actually saw were the dead cell walls of plant cells (cork) as they appeared under the microscope

Question 7

who was Anton Van Leeuwenhoek and what did he discover?

Answer 7

The first man to witness a live cell under a microscope was Anton Van Leeuwenhoek, who in 1674 described the algae Spirogyra.

Leeuwenhoek probably also saw bacteria when looking at the algae but didn’t describe them at the time

Question 8

how is a plasma membrane structured?

Answer 8

The plasma membrane is a lipid bilayer with proteins and other molecules embedded in it. Some archaea have a lipid monolayer.

Question 9

what is the size of the smallest object a person can see?

Answer 9

• Smallest object a person can see is about 0.2 mm (200 μm) in size

.* Objects must be about this distance apart for them to be distinguished from one another (resolution).

• Most cells smaller than 200 μm in size

Question 10

what is the resolution of a Light Microscope?

Answer 10

Resolution 0.2 μm (About 1000 times that of the human eye

Question 11

what is the famous quote from Matthias Jakob Schleiden? (Cell Theory)

Answer 11

“All plants are made up of cells”

Question 12

what is the famous quote from Rudolf Virchow? (Cell Theory)

Answer 12

“Cells come from cells”

Question 13

what is the famous quote from Theodor Schwann? (Cell Theory)

Answer 13

“The cause of nutrition and growth resides not in the organism as a whole but in the elementary parts – the cells.”

Question 14

who came first out of Scheiden, Virchow and Schwann?

Answer 14

the order is as follows:

Schleiden - “all plants are made up of cells”
Virchow - “Cells come from Cells”
Schwann - “The cause of nutrition and growth resides not in the organism as a whole but in the elementary parts – the cells.”

Question 15

what is the resolution of a electron microscope?

Answer 15

The resolution 0.2 nm.

(About 1,000,000 times greaterthan the human eye)

Question 16

what is cell size limited by and how?

Answer 16

Cell size is limited by the surface area-to-volume ratio.

Question 17

what is meant by surface in relation to cell size?

Answer 17

The surface of a cell is the area that interfaces with the cell’s environment.

Question 18

what is meant by cell volume?

Answer 18

The volume of a cell is a measure of the space inside a cell.

Question 19

what is meant by surface-area: volume ratio?

Answer 19

• Surface - area: volume ratio is defined as the surface area divided by the volume.
• For any given shape, increasing volume decreases the surface -area: volume ratio

Question 20

why do we use the surface-area: volume ratio？

Answer 20

• The volume of a cell determines how much chemical activity it can carry out per unit of time.
• The surface area of the cell determines the amount of a substance it can take in from the external environment and how much waste itcan release into the environment.

Question 21

what is unique about the structure of Prokaryotic cells when compared to Eukaryotic cells?

Answer 21

they have no nucleus or other membrane-bound compartments. They lack distinct organelles

Question 22

what is unique about the structure of Eukaryotic Cells in comparison to Prokaryotic cells?

Answer 22

Eukaryotic Cells have a membrane-enclosed nucleus and other membrane-enclosed compartments and organelles

Question 23

what are the shared features of prokaryotic and eukaryotic cells?

Answer 23

Cytoplasm
Ribosomes
Nucleoid
Plasma
Membrane

Question 24

Do prokaryotic cells have cell walls?

Answer 24

• Some prokaryotic cells have Cell Walls
• Located outside plasma membrane
• Maintains shape of cell
• Cell wall of most bacteria (Not Archaea) contains peptidoglycan (sugars and amino acids)

*In some bacteria (Gram –ve) an outer layer of lipopolysaccharide (lipid and pilysaccharide) and protein encloses the peptidoglycan layer

Question 25

what is a mycoplasma?

Answer 25

* Bacteria that lack a cell wall * This makes them unaffected by some antibiotics such as penicillin

Question 26

what is the capsule in prokaryotic cells?

Answer 26

* Some bacteria also have a layer of slime enclosing the cell wall. * This is mostly polysaccharides and is referred to as the capsule Capsule can protect bacteria from attack by white blood cells in animals they infect. Also stops the bacterium drying out and can help it attach to other cells. The capsule is not necessary for the survival of the bacterium and if it is lost the bacterium cansurvive

Question 27

can prokaryotic cells undergo photosynthesis? if they can how do they do this?

Answer 27

Cyanobacteria and some other bacteria have a complex and highly organised system of internal membranes with which to carry out photosynthesis

Question 28

what are the corkscrew structures found in some prokaryotic cells known as?

Answer 28

Some prokaryotic cells have flagella, locomotory structures shaped like corkscrews

Question 29

what are the helical structures found in some prokaryotic cells used for?

Answer 29

Some prokaryotes have a helical structure just inside the plasma membrane which is made up of proteins very similar to actin in eukaryotes. It has been suggested that this protein is responsible for maintaining the structure of the cell This structural protein is not found in spherical bacteria. However, this is not a ‘true’ cytoskeleton and as such prokaryotes do not undergo mitosis. They divide by a process known as binary fission after replicating their DNA.

Question 30

what are the function of endospores in prokaryotic cells?

Answer 30

* Some bacteria produce dormant,resistant endospores within vegetative cells. * Endospores are highly resistant to environmental stresses such as high or low temperature or drought.

Question 31

what are the main characteristics of eukaryotic cells?

Answer 31

- Generally have dimensions upto 10 times greater than prokaryotic cells .- Like prokaryotes they have a plasma membrane, cytoplasm and ribosomes. - Contain a membrane-bound nucleus .- Also have membrane -boundorganelles and a protein scaffolding called the cytoskeleton. - Compartmentalization is the key to eukaryotic cell function. - Each organelle or compartment has a specific role defined by chemical processes. - Membranes surrounding these organelles keepaway inappropriate molecules and also act as traffic regulators for raw materials into and out of the organelle.

Question 32

what is the function of the nucleus in eukaryotic cells?

Answer 32

* Usually the largest organelle in the cell. * Contains most of the cell’s genetic material(DNA). * Replication of DNA and the first steps in decoding it for protein production take place in the nucleus.

Question 33

what is the function of the RER (rough endoplasmic reticulum) in eukaryotes?

Answer 33

* ER can enclose up to 10% ofthe interior volume of the cell. * Rough ER (RER) is studded with ribosomes which are temporarily attached to itsouter surface. * RER segregates newly synthesised proteins away from the cytoplasm and transports them to other areas of the cell. * While inside the RER proteins can be chemically modified to alter their function and destination

Question 34

what is the function of the SER (smooth endoplasmic reticulum) and how is it different from the RER?

Answer 34

* More tubular than RER. * Lacks ribosomes on the outside. * Responsible for chemical modification of small molecules taken into the cell –drugs. * Site of hydrolysis of glycogen(multi-branched polysaccharide of glucose) in animal cells. * Site for synthesis of lipids and steroids

Question 35

what do ribosomes do in eukaryotic cells?

Answer 35

* In prokaryotic cells Ribosomes float freely in the cytoplasm. * In Eukaryotic cells they are found in 2 places – 1. The cytoplasm where they may be free or attached to the surface of the endoplasmic reticulum. – 2. Inside mitochondria and chloroplasts. * Site of protein synthesis

Question 36

what is the function of the golgi apparatus?

Answer 36

* Usually consists of flattened membranous sacs called cisternae. * Receives proteins from RER and may further modify them. * Concentrates, packages and sorts proteins before they are sent to final destination. * Site of synthesis of polysaccharides for plant cell walls.

Question 37

what are lysosomes in E cells??

Answer 37

* Lysosomes are vesicles containing digestive enzymes that come in part from the Golgi. * Lysosomes are sites for breakdown of food and foreign material brought into the cell by phagocytosis. * Lysosomes are also the site where digestion of spent cellular components occurs, a process called autophagy

Question 38

what is the function of Mitochondria in E cells?

Answer 38

* These are the ‘power houses’ of the cell. * Have their own independent genome which is very similar to bacterial genomes. * Energy stored in the bonds of carbohydrates and fatty acids (food) isconverted into a more useful form for the cell (ATP) by ATP synthase in the inner membrane. * The number of mitochondria in a cell varies by organism and tissue type. * 650 Mitochondrial proteins identified inhuman heart cells – 940 in rats

Question 39

what are plastids?

Answer 39

* Plastids are organelles found only in plants and some protists. * Chloroplasts, the sites where photosynthesis occurs, are one type of plastid

Question 40

what are vacuoles?

Answer 40

* Vacuoles have several functions. - Storage - Structure - Reproduction - Digestion