As Biology Viruses, Cell Structure, Cell Transport And Mitosis

Front 1

Name the stages of Mitosis in order

Back 1

Prophase, Metaphase, Anaphase, Telophase, (Cytokenisis)

PMAT

Front 2

What happens during Interphase?

Back 2

1. DNA content is doubled via DNA Replication

2. Increase in Protein Synthesis

3. Cell organelles are replicated.

Front 3

Describe / Draw the shape of a chromosome during prophase

Back 3

Two identical sister chromatids joined together by a centromere

Front 4

What happens during Prophase?

Back 4

Each Chromosome shortens and thickens.

The centrioles (Which make the spindles) move to opposite poles of the cell. (Only in animals)

The nuclear membrane breaks down.

Front 5

What happens during Metaphase?

Back 5

The centrioles (in animals) form spindles across the cell, consisting of protein microtubules.

Each chromosome moves to the equator of the cell and attaches to the spindle via its centromere.

Sister chromatids are oriented towards opposite poles of the cell

Front 6

What happens during Anaphase?

Back 6

The centromeres of the chromasomes split. Sister Chromatids separate.

Then the sister chromatids are pulled to the opposite poles of the cell by the spindle microtubules.

Front 7

What happens during Telophase?

Back 7

With the chromatids at the opposite poles of the cell, they begin to uncoil.

The nuclear membrane reforms around the genetic material. Forming two genetically identical nuclei.

Front 8

What happens during cytokinesis?

Back 8

After the nuclear division and there are two nuclei, the cytoplasm begins to split in two.

Two new cells form as the cell surface membrane splits.

Front 9

What 5 components do Prokaryotic Cells ALWAYS contain?

Back 9

Circular DNA,

Cytoplasm,

Cell Surface Membrane,

Cell Wall,

Smaller 70s Ribosomes

Front 10

Describe 3 structures that are not always present but sometimes present in prokaryotic cells.

Back 10

One or more flagella

One or more Plasmids

A capsule surrounding the cell wall. (Layer of slime)

Front 11

Describe the conditions required for centrifugal to isolate organelles

Back 11

1.Cells broken open, basically blended. Homogenised.

2. Isotonic solution to prevent osmosis in organelles.

3. Low temperature to stop enzynes such as lysozomes from self digesting

4. Buffer solution to maintain the pH. Stops denaturing of enzymes

Front 12

Name the steps of centrifugation

Back 12

Homogenise (Blend to break apart all cells)

Filter (Get rid of remaining cells and cell wall fragments)

Centrifuge (At different speeds to get different densities of organelles

Front 13

How is centrifugation Carried Out?

Back 13

1. Homogenise cell samples and then filter them to remove cell debris such as cell walls, cell membranes and whole cells.

2. Centrifuge at a low speed. Densest organelles deposit in the Pellet. These can be filtered off to leave just the Supernatant.

3. Centrifuge the Supernatant at a higher speed and repeat process to get pellets of organelles at Decreasing density.

Front 14

In what order would you expect organelles to be isolated in centrifugation?

Back 14

Nuclei, Chloroplastsm, Mitochondria, Endoplasmic Reticulum and finally Ribosomes.

Front 15

What is meant by the fluid-mosaic model of the Phospholipid Cell Surface Membrane

Back 15

The phospholipid molecules in the bilayer are constantly moving giving a fluid structure.

Protein molecules are embedded in the membrain, like a mosaic.

Front 16

What gives the cell surface membrane partial permeability?

Back 16

The phospholipids form a bilayer. Very small molecules such as Carbon Dioxide and Oxygen can diffuse through gaps between the Phospholipids. Water passes through Water Protein Channels.

Cholesterol in the plasma membrane provides strength and restricts the fluid movement of phospholipids, meaning less ions lost from the cell.

Lipid-Soluble molecules can pass through the layer made of lipids. However polar molecules and water soluble ions cannot pass through.

There are protein carriers and channel proteins are embedded in the membrane that allow water soluble ions and polar molecules to pass through via Active Transport and Facilitated Diffusion

Front 17

What does the rough endoplasmic reticulum do?

Back 17

Its surface had ribosomes which produce secretory proteins (that are released out of the cell)

Front 18

What does the Smooth Endoplasmic Reticulum do?

Back 18

It is involved in the production and transport of lipids, phospholipids and steroids.

Front 19

What do the golgi apparatus do?

Back 19

Add Carbohydrates to the proteins recieved from the RER to form Glycoproteins

Packages Proteins and Glycoproteins into Golgi Vesicles for secretion

Produce Lysosomes. Golgi Vesicles which contain Lysozymes

Front 20

What are Lysosomes and what are their functions?

Back 20

They are simple sacs containing Lysozymes, Hydrolytic Enzymes. Have to be kept apart from rest of cell or they would destroy it.

Functions:

1. Digestion in phagocytosis. Fuse with phagosomes to break down material inside.
2. Non functioning organelles are engulfed and digested.
3. Released out of the cell for other purposes.

Front 21

Describe the Structure of Mitochondria

Back 21

Have a Double Membrane formed of an inner and outer membrane with an inter-membrane space. Controls entry and exit.

Inner Membrane is folded into Cristae. These provide a large surface area for enzymes and proteins to attach.

Matrix Inside which contains Enzymes for Aerobic Respiration as well as DNA and Ribosomes for protein synthesis.

Front 22

Describe the Structure of Chloroplasts.

Back 22

Chloroplast Envelope formed of a double plasma membrane with inner and outer membranes, controls what comes in and out.

Contains Thylakoids, flattened sacs containing chlorophyll, absorb light for photosynthesis. Large Surface Area.

Grana are stacks of Thylakoids

Stroma is liquid matrix with Enzymes, Sugars and Starch Granules, where synthesis of sugars in photosynthesis takes place.

Front 23

What are the Advantages and Disadvantages of Electron Microscopy?

Back 23

Advantages:

Electrons have a shorter wavelength than light, so images have a greater resolution

Light images get blurry due to lower resolution

Disadvantages:

A vacuum is required so no living specimens.

Preparation and staining techniques are more complex.

Poor Technique = False Images, Artifacts.

Very thin sections must be prepared.

Images are not in colour.

Cannot get video images

Front 24

What are the Advantages and Limitations of Transmission Electron Microscopes?

Back 24

Advantages:

Higher Resolution than SEM.

Can see internal structures, even tiny proteins.

Disadvantages:

Very Thin section of specimen must be used.

Does not show 3D arrangement of cellular compounds.

Front 25

What are the Advantages and Limitations of Scanning Electron Microscopes?

Back 25

Advantages:

Shows the Surfaces of Structures.

Three Dimensional Images.

Much Thicker sections can me examined.

Does not need thin sections

Disadvantages:

Lower Resolution than TEM

Can only show surfaces, no internal structures.

Front 26

What is Resolution in microscopy?

Back 26

The ability to distinguish between two close objects.

Front 27

What else is present in Cell Surface Membranes that is useful to the cell?

Back 27

Embedded Protein Molecules act as receptors for specific hormones are used in Cell Signalling.

Receptor Proteins have specific tertiary structure which is complementary as a binding site to the specific hormones shape.

Branched Carbohydrate chains or glycolipid chains or glycoprotein chains act as receptors in cell-cell recognition and as antigens.

Front 28

Define Diffusion

Back 28

The net movement of molecules from an area of high concentration to an area of low concentration until the molecules are equally distributed.(equillibrium)

A passive process.

Front 29

Define Osmosis

Back 29

The net movement of water from an area of high water potential to an area of low water potential across a partially permeable membrane.

Front 30

What is the difference between DNA in Eukaryotes and Prokaryotes?

Back 30

Eukaryotes have Linear Protein Bound DNA

Prokaryotes have Circular Non-Protein Bound DNA

Front 31

What is the process by which cells become adapted for different functions

Back 31

Cell Specialisation

Front 32

What is the general structure of a Virus?

Back 32

Genetic Material contained within a Protein Capsid.

Attachment Proteins / Glycoproteins on the outside often on the Envelope, Phospholipid bilayer. Which are complementary to receptors on the surface of host cells.

Front 33

Describe the features and role of Ribosomes

Back 33

They are very small organelles made of Proteins and rRNA.

They are loose in the cytoplasm or attached to the Rough Endoplasmic Reticulum.

They are used in Protein Synthesis for joining Amino Acids Together

Front 34

Describe the features and role of the Nucleus

Back 34

It contains the genetic material and thus controls protein synthesis and the development, structure and function of the cell.

Nuclear envelope is a double membrane with nuclear pores to allow passage of RNA molecules. Nucleoplasm is a jelly like material that makes up the bulk of nucleus

It contains DNA which in a dividing cell take the form of Chromosomes.

It contains a Nucleolus / Nucleoli which is used for producing ribosomes.

Front 35

What are the functions of the Rough and Smooth Endoplasmic Reticulum?

Back 35

Rough Endoplasmic Reticulum has ribosomes on its surface which produce secretory proteins.

These are sent to the Golgi Apparatus for modification and Packaging.

Smooth Endoplasmic Reticulum is involved in the production and transport of Lipids. Doesn't have ribosomes.

Front 36

In what kind of cells are Golgi Apparatus most abundant?

Back 36

In secretory cells which secrete enzymes e.g in the Pancreas.

Front 37

What are the three phases of the Cell Cycle?

Back 37

Interphase: cell growth

Nuclear Division: nucleus divides in two

Cytokinesis: Cytoplasm divides in two

Front 38

What is the Mitotic Index?

Back 38

The Ratio of the number of cells undergoing Mitosis in a tissue to the Total Number of Cells

Front 39

How would a Mitotic Index be Calculated?

Back 39

Number of Cells in Mitosis / Total number of Cells * 100

Front 40

What does the diploid number represent?

Back 40

2n. The total number of chromosomes in a normal body cell. 2 from each pair. 23 Homologous pairs so 46 chromosomes.

Front 41

What does the haploid number represent?

Back 41

n. Number of chromosomes in a single set of chromosomes. One from each every homologous pair. 23 In humans from 23 homologous pairs.