1.1 : Introduction to cells

Question 1

what are unicellular organisms & examples?

Answer 1

• organisms made up of a single cell, whilst still carrying out essential functions of life.
• amoeba, e-coli, chlamydomonas

Question 2

what are multicellular organisms & examples?

Answer 2

• organisms made up of many cells, that carry out essential functions of life.
• mammals, flowering plants, birds

Question 3

what occurs as cells develop in regards to specialisation?

Answer 3

as cells develop, they specialise in their structure and in the functions they carry out –> once a cell is fully specialised, it can no longer divide (it is a mature cell)

Question 4

in what type of cell does cell division occur & how?

Answer 4

• in newly formed = unspecialised cells
• as a newly formed cell grows and enlarges –> it divides into two –> before it is modified into a particular task (specialised)

Question 5

what is the consequence of specialisation?

Answer 5

the variety shown in cells in regards to their shape and structure –> due to their evolutionary adaptations to different environments and different specialised functions.

Question 6

what is cell theory?

Answer 6

a statement that cells are the unit of structure and function in living things.

Question 7

what five basic ideas does cell theory contain?

Answer 7

• cells are the building blocks of structures in living things.
• cells are the smallest units of life.
• cells are derived from pre-existing cells by division.
• cells contain a blueprint for their growth, development and behaviour.
• cells are the site of metabolism (all chemical reactions of life).

Question 8

what did Pasteur’s experiment disprove?

Answer 8

• disproved spontaneous generation

- by showing that bacteria is freely circulating in the air & contaminates exposed matter.

Question 9

what are the three common structures in plant & animal cells?

Answer 9

-plasma / cell membrane
-cytoplasm
-nucleus
(some organelles in cytoplasm)

Question 10

what are the two different storage carbohydrates that animal & plant cells store?

Answer 10

• animal : store glycogen

- plant : store starch

Question 11

what features do plant cells contain that animal cells don’t?

Answer 11

• cellulose cell wall
• chloroplasts
• permanent vacuole
• starch storage

Question 12

what features do animal cells contain that plant cells don’t?

Answer 12

• centrosome (present outside nucleus)

- glycogen storage.

Question 13

what is the function of the centrosome?

Answer 13

important in cell division –> organises the pulling apart of chromosomes in the division of the nucleus in mitosis.

Question 14

what is is meiosis?

Answer 14

when a single cell divides twice to produce four sex cells/daughter cells containing half the original amount of genetic information.

Question 15

what is mitosis?

Answer 15

when a single cell divides into two identical daughter cells & the replicated chromosomes are separated into two new nuclei.

Question 16

how do unicellular organisms reproduce?

Answer 16

by binary fission = splits into two.

Question 17

what is the function of a condenser in the compound light microscope?

Answer 17

it focuses the light onto the specimen with the iris diaphragm (used to vary the intensity of light reaching the specimen)

Question 18

what are the two types of lenses used to focus light transmitted through the specimen & what is the difference?

Answer 18

• objective & eyepiece lens.
• the objective lens forms an image in the microscope tube, which is further magnified by the eyepiece lens, producing a greatly enlarged image.

Question 19

why must the biological material being examined by compound light microscopy be sufficiently transparent?

Answer 19

so that the light rays are able to pass through & the biological material is able to be examined.

Question 20

what is the graticule?

Answer 20

a transparent scale that is calibrated (adjusted) using a stage micrometer (tiny ruler), which is placed on the microscope stage in place of the slide.

Question 21

what are the coarse & fine focus used for in light microscope?

Answer 21

• coarse focus : used to focus the low & medium power objectives.
• fine focus : used to focus the high power objective.

Question 22

what is the difference between magnification & resolution?

Answer 22

• magnification : the number of times larger an image is than the specimen.
• resolution : (sharpness) the ability of a microscope to separate small objects which are very close together.

Question 23

equation for magnification?

Answer 23

magnification = size of image / size of specimen 
M = I / S

Question 24

what occurs if two separate objects can’t be resolved (separated) & why does this occur?

Answer 24

can’t be resolved (separated) –> they are seen as one object
–> due to the wavelength of light & how far apart the objects are (shorter wavelength = better resolution)

Question 25

what is transmission electron microscopy?

Answer 25

when electrons are beamed through the microscope --> have a shorter wavelength than light --> focused by magnets & condensed until the fluorescent screen --> stained with organelles (fluorescent screen = stained with heavy metals = electrons can't pass through)

Question 26

what is free etching?

Answer 26

when the surface of a sample / specimen is etched --> meaning the shape of all cells & structures will remain the same as they are frozen --> prepares the specimen sample before putting it under the microscope.

Question 27

what occurs to the surface area : volume ratio if the volume increases faster than the surface area & what does this result in?

Answer 27

- it falls - with increasing cell size, less & less of the cytoplasm has access to the cell surface for exchange of gases, supply of nutrients & loss of waste products.

Question 28

what is the rate of metabolism and rate of exchange of materials a function of?

Answer 28

- rate of metabolism of a cell is a function of it's mass (volume) - rate of exchange of materials & heat energy that metabolism generates is a function of the cells surface area.

Question 29

specialised cells are separated into tissues and organs, what are these & examples?

Answer 29

- tissues : group of similar cells that are specialised to perform a specific function = heart muscle of a mammal. - organs : collection of different tissues which perform a specialised function = heart pf a mammal.

Question 30

what is a gene?

Answer 30

a specific region of a chromosome in the DNA which codes for a specific protein, that determines the development of a specific characteristic of an organism.

Question 31

what controls the activation of genes & how cells are specialised?

Answer 31

which genes are activates and how a cell is specialised is controlled by the immediate environment of differentiating cells & its position in the developing organism.

Question 32

what is the cost of specialisation in relation to division of labour?

Answer 32

Specialised cells are efficient at carrying out their particular function --> resulting in differences between cells due to division of labour (different functions) --> meaning specialised cells are dependent on activities of other cells.

Question 33

what is the cell cycle?

Answer 33

the time between one cell division and the next.

Question 34

an example of a cell that continue to grow & divide repeatedly instead of specialising?

Answer 34

stem cells = stem cells in bone marrow --> divide to form cells that develop into red & white blood cells, platelets.

Question 35

an example of a cell that specialises and turns into a mature cell?

Answer 35

red blood cell --> loses nucleus & cytoplasm fills with haemoglobin ( O2 carrying pigment ) & enzyme ( carbonic anhydrase ).

Question 36

how do cells in healthy organisms die & how does it occur?

Answer 36

cells eventually die by programmed cell death (PCD) --> controlled by specific genes. --> all parts of the infected, damaged or superfluous cell is packaged in a membrane & engulfed by surrounding cells.

Question 37

what are embryonic stem cells?

Answer 37

stem cells derived from the undifferentiated inner cells of a human embryo, which are capable of further dividing and differentiating.

Question 38

what is a stem cell?

Answer 38

cell that has the capacity for repeated cell division & capacity to differentiate into mature cell types, while maintaining an undifferentiated state

Question 39

what occurs in embryological development and what are the adult stem cells?

Answer 39

most cells lose the ability to divide --> develop into tissues and organs that make up an organism --> a few cells within these tissues, retain many of the properties of embryonic stem cells = adult stem cells.

Question 40

what are isolated stem cells?

Answer 40

stem cells that are isolated in large numbers & maintained in viable (workable) cell cultures, allowing them to be used in medical therapies.

Question 41

why are isolated cells kept under reproducible conditions?

Answer 41

- differentiate into specific & desired blood cell types. - continue to divide in sterile cell-culture environment. - survive in patients body after being introduced. - integrate into a particular tissue type in the patients body. - function correctly in body for the remainder of patients life. - don't trigger harmful reactions within the tissues of patients body.

Question 42

three diseases that can be treated using stem cell technology?

Answer 42

- Parkinson’s disease - type 1 diabetes - cardiac muscle damage

Question 43

what are the features of a light microscope & what do they do?

Answer 43

- eyepiece & objective lens : objective lens forms an image in the microscope which is further magnified by eyepiece lens - condenser : focuses light onto the object with iris diaphragm (vary intensity of light reaching object) - coarse focus : used to focus low & medium objectives - fine focus : used to focus the high power objective - turret : as it turns, objectives click into place - stage : microscope slide placed here