cell specialisation

Question 1

why do larger multi-cellular organisms need specialisation? (2 examples of funtions)

Answer 1

• carry out particular functions
• specialised functions
• exchange systems

Question 2

what is cell differentiation?

Answer 2

process during development whereby cells become more specialised and distinct as they mature

Question 3

how does cell differentiation happen?

Answer 3

different genes expressed in different cell types

Question 4

what affects what cell type it will differentiate into?

Answer 4

location of stem cell in the early embryo, indicates by gradients of signalling chemicals

Question 5

in the adult body where are stem cells located?

Answer 5

in stem cell niches - environment where they can remain undifferentiated for long time then proliferate when needed

Question 6

examples of niches (muscle)

Answer 6

striated skeletal muscle stem cells inactive until muscle is damaged - then proliferate and repair

Question 7

examples of niches (hair)

Answer 7

hair follicles contain stem cells - allow hair growth

Question 8

totipotent meaing

Answer 8

• capable of continued division
• any tissue in organism
• low in number
• only at v early stages of embryo development
• can form complete organism

Question 9

pluripotent meaning

Answer 9

• from totipotent cells
• early embryonic stages
• almost all cell types
• cannot produce complete organism

Question 10

multipotent meaning

Answer 10

• limited no. cell types
• bone marrow -> blood cell
• later stage of development
• for remainder of organisms life

Question 11

unipotent meaning

Answer 11

• only form single cell type
• sperm cells
• late embryonic stage

Question 12

example of multipotent cell

Answer 12

Hematopoietic stem cell - found in adult bone marrow, can develop into many types of blood cells

Question 13

Why is SFA:V ratio important in the limitation of cell size?

Answer 13

Determines the rate at which an organism can take in nutrients from its surroundings

Question 14

what happens to the SFA:V ratio as the cube gets bigger?

Answer 14

decreases

Question 15

rbc adaptations to increase their sfa:v ratio

Answer 15

• small size
• flattened, biconcave (reduce vol)
• maximise absorption of oxygen

Question 16

Where is proximal convoluted tubule?

Answer 16

In nephron in kidney

Question 17

Proximal convoluted tubule adaptations to increase their sfa:v ratio - basal membrane

Answer 17

invaginations - outer basal membrane - close to capillaries

Question 18

Proximal convoluted tubule adaptations to increase their sfa:v ratio - apical membrane

Answer 18

microvilli - inner apical membrane - in contact w/ the filtrate

Question 19

what is the alveolar epithelium an example?

Answer 19

Example of tissue with more than one cell type to tend to different functions

Question 20

what kind of process is the diffusion of CO2 and O2 of Type 1 pneumocytes?

Answer 20

passive price

Question 21

adaptations of type 1 pneumocytes?

Answer 21

Very wide but very thin cells, reduces diffusion distance

Question 22

adaptations of type 2 pneumocytes

Answer 22

many secretory vesicles (lamellar bodies)

Question 23

adaptations to how the alveolus diffuses oxygen

Answer 23

alveolus lined with a film of moisture

Question 24

Why do muscles work in pairs?

Answer 24

• antagonistic pairs
• contractile but must revert to original length using another muscle

Question 25

what are skeletal muscles?

Answer 25

muscles used to move which are attached to bones

Question 26

What is the structure of myofibrils in skeletal muscle?

Answer 26

long and unbranched

Question 27

What is the structure of myofibrils in cardiac muscle?

Answer 27

Short and branched

Question 28

how many nuclei does the cardiac muscle contain?

Answer 28

One

Question 30

how many nuclei does the skeletal muscle contain?

Answer 30

multiple