Unit 1 Cell Biology

Question 1

Define Cell

Answer 1

the basic unit of life

Question 2

Define Differentiation

Answer 2

the change in a cell to become more specialized

Question 3

Define Emergent Properties

Answer 3

properties that appear in a complex system but do not appear in the individual units

Question 4

Define Stem Cells

Answer 4

cells that are capable of differentiation

Question 5

Function of Life

Answer 5

1.nutrition
2.metabolism
3. growth
4.response
5.excretion
6.homeostasis
7. Reproduction

Question 6

Equation to calculate the size of a cell

Answer 6

actual width of cell = size of image/size of magnification

Question 7

How does the surface area to volume ration affect the function of a cell

Answer 7

if the ratio is too small the exchange of substances will be too slow, waste substances will accumulate and heat will not be lost efficiently

Question 8

Cell size is limited by…

Answer 8

Surface area to volume ration

Question 9

Differentiation involves…

Answer 9

expression of some genes and not others in a cell’s genome

Question 10

what is necessary for embryonic development

Answer 10

stem cell division and differentiation

Question 11

Cell Theory

Answer 11

Living organisms are composed of cells (one or more) – that is, cells are the building blocks of organisms.

Cells are the smallest units of life – that is, a cell is the basic unit capable of carrying out all the functions of a living organism.

Cells come from pre-existing cells (omni cellulae e cellula) – that is, cells do not show spontaneous generation.

Question 12

Why are striated muscles an exception to Cell Theory

Answer 12

Striated muscle tissue is composed of repeated units called sarcomeres. These show a characteristic striped (striated) pattern when viewed under the microscope. This challenges the idea that a cell has one nucleus, as the muscle cell (fibre) has more than one nucleus per cell.

Question 13

Why are giant algae an exception to Cell Theory

Answer 13

As a single-celled organism, Acetabularia challenges two widely accepted notions about cells: that they must be simple in structure and small in size.

Question 14

Why are Fungal hyphae an exception to cell theory

Answer 14

This challenges the idea that a cell is a single unit as the fungal hyphae have many nuclei, are very large and possess a continuous, shared cytoplasm.

Question 15

Describe the use of stem cells to treat Stargardt disease and one other example

Answer 15

Stargardt Disease - Patients are given retinal cells derived from human embryonic stem cells, which are injected into the retina. The results obtained have been quite positive as the inserted cells attach to the retina and become functional, suggesting that it may be possible to restore sight to affected individuals using stem cells.
Leukemia -Treatment in this case involves harvesting hematopoietic stem cells (HSCs), which are multipotent stem cells. HSCs can be taken from bone marrow, peripheral blood or umbilical cord blood. The HSCs may come from either the patient or from a suitable donor. The patient then undergoes chemotherapy and radiotherapy to get rid of the diseased white blood cells. The next step involves transplanting HSCs back into the bone marrow, where they differentiate to form new healthy white blood cells.

Question 16

Why are stem cells seen as unethical

Answer 16

But, given that some of the methods of obtaining stem cells may involve destruction of an embryo, ethical issues are raised. People question whether it is morally right to promote therapeutic use of stem cells.

Question 17

Define Magnification

Answer 17

how much an image has been enlarged

Question 18

Define Resolution

Answer 18

the minimal distance at which two points that are close together can be distinguished

Question 19

Characteristics of a Prokaryotic cell

Answer 19

no nucleus or membrane bound organelles
cell walls
pili
flagella
plasma membrane containing cytoplasm that has 70S ribosomes

Question 20

Characteristics of Eukaryotic cells

Answer 20

plasma membrane enclosing cytoplasm that has 80S ribosomes
nucleus
mitochondira
other membrane-bound organelles

Question 21

Characteristics of Eukaryotic cells

Answer 21

plasma membrane enclosing cytoplasm that has 80S ribosomes
nucleus
mitochondira
other membrane-bound organelles

Question 22

Electron Microscopes

Answer 22

higher resolution than light microscopes allowing observation of the ultra structure of cells. Can magnify up to x10,000,000

Question 23

Binary Fission

Answer 23

Binary fission is a means used by prokaryotes to reproduce asexually. It involves the following steps:

The chromosome is replicated semi-conservatively, beginning at the point of origin (shown in red in Figure 2).
Beginning with the point of origin, the two copies of DNA move to opposite ends of the cell.
The cell elongates (grows longer).
The plasma membrane grows inward and pinches off to form two separate, genetically identical cells.

Question 24

Membranes are formed by

Answer 24

Phospholipids, cholesterol, proteins, lipoproteins, and glycoproteins

Question 25

Cell membranes are formed by…

Answer 25

double layers of phospholipids

Question 26

Phosolipids are…

Answer 26

amphipathic meaning they have a hydrophilic part and a hydrophobic part. The hydrophilic heads face both the outside and inside of the cell while hydrophobic parts are in the middle of the bilayer

Question 27

Define Transmembrane proteins

Answer 27

integral membrane proteins that span across the membrane making it hard to separate them form the membrane

Question 28

Define Integral Proteins

Answer 28

embedded in the phospholipid bilayer and protrude on only one side of the membrane and are difficult to separate form the phospholipid bilayer

Question 29

Define Peripheral Proteins

Answer 29

are temporarily attached either to the surface of the phospholipid bilayer or to integral proteins and can be separated from the membrane using salts

Question 30

Explain the fluidity and permeability of plasma membrane

Answer 30

phospholipids have a low melting point because of the kinking of the long chain of fatty acids occurring at unsaturated bonds which explains why some are found in liquid states and others are found in a solid state, making the membrane fluid. In animal cells, cholesterol embedded in this double layer will control this fluidity and permeability to some solutes

Question 31

Define Passive Transport

Answer 31

movement across the membrane without the use of energy

Question 32

Define Facilitated Diffusion

Answer 32

passive transport of molecules or ions across the cell membrane through specific transmembrane proteins

Question 33

Define active transport

Answer 33

the movement across the membrane requiring energy in the form of ATP

Question 34

Define Osmosis

Answer 34

The passage of water through a selectively permeable membrane from a higher water potential to a lower water potential

Question 35

Osmolarity

Answer 35

the measurement of the solute concentration of a solution expressed as the total mass of solute per litre of solution

Question 36

Isotonic solution

Answer 36

shares the same concentration as the tissues or cells it it bathing

Question 37

hypertonic solution

Answer 37

has a higher solute concentration that the tissues it bathes

Question 38

hypotonic solution

Answer 38

lower solute concentration than the tissue is bathes

Question 39

endosymbiotic theory

Answer 39

mitochondria and chloroplasts were themselves prokaryotes that were taken in by larger prokaryotes by endocytosis. Instead
Have double membranes, as expected for cells taken in by endocytosis. (see Figure 1 below)

Have circular naked DNA, as in prokaryotes.

DNA is formed as single chromosomes.

Have 70S ribosomes, as in prokaryotes.

Divide by binary fission like prokaryotic cells.

Are susceptible to some antibiotics.

Question 40

Interphase

Answer 40

stage of cell division before mitosis.
the cell grows, formes organelles(G1 stage), DNA is duplicated (S stage) and synthesis of proteins that are involved in nuclear division occur

Question 41

Mitosis

Answer 41

nuclear division consisting of four stages: prophase, metaphase, anaphase, and telophase

Question 42

Prophase

Answer 42

The stage where chromatin condenses and associates with histones forming chromosomes, the nuclear membrane disappears and spindle fibres are formed. Chromosomes attach to spindle fibres

Question 43

Metaphase

Answer 43

The stage where chromosomes are aligned in the equator of the cell

Question 44

Anaphase

Answer 44

where sister chromatids are separated to the opposite poles of the cell

Question 45

Telophase

Answer 45

the last stage of mitosis where a nuclear membrane forms around each set of chromosomes that being to uncoil

Question 46

Cytokinesis

Answer 46

a process that occurs along with telophase. The cytoplasm of the parental cell divides into two daughter cells. Cytokinesis in animals is produced by cell strangling whole in plants it is by formation of a plate

Question 47

Define Centomere

Answer 47

the stucture of the chromosome that holds together both chromatids and is the point of attachment to the spindle fibres

Question 48

Define Mitotic Index

Answer 48

Number of cells in mitosis divided by total number of cells seen under the microscope