B2.3 Cell Specialization

Question 1

describe how gametes develop into foetus

Answer 1

1. gametes fuse to form zygote
2. zygote cells divide to form blastocyst
3. blastocyst grows into embryo
4. embryo develops into foetus

Question 2

what kind of stem cell are zygotes?

Answer 2

totipotent; can develop into any cell

Question 3

what kind of stem cells are blastocysts made of?

Answer 3

pluripotent; can’t form complete organisms

Question 4

what kind of stem cells are most adult stem cells?

Answer 4

multi-/unipotent; can only develop into closely related cells

Question 5

example of multipotent stem cell

Answer 5

hematopoietic stem cells can only become red blood cells

Question 6

morphogen

Answer 6

chemical that regulates development of specialized cells based on concentration by binding to cell receptors and activating/repressing genes

Question 7

example of morphogen

Answer 7

bicoid protein that determines head of fruit flies; if defective, butts on both ends

Question 8

stem cell niche

Answer 8

where stem cells can be maintained/promoted and differentiate

Question 9

examples of stem cell niches

Answer 9

bone marrow produces hematopoietic cells, hair follicles produce epithelial, melanocyte, mesenchymal cells

Question 10

self-renewal

Answer 10

when stem cells reproduce and some differentiate but some stay stem cells, allowing continuation

Question 11

two functions of stem cells

Answer 11

1. self-renewal
2. recreating functional tissues

Question 12

length and diameter of sperm

Answer 12

50 and 3 micrometres

Question 13

diameter of ovum

Answer 13

120 micrometres

Question 14

length of neuron

Answer 14

350 micrometres

Question 15

diameter of red blood cell

Answer 15

7.5 micrometres

Question 16

diameter of white blood cell

Answer 16

12-15 micrometres

Question 17

length and width of skeletal muscle cell

Answer 17

40 mm and 10-50 micrometres

Question 18

what are factors for cell size?

Answer 18

need for exchange of materials, cell division

Question 19

adaptations of red blood cells for carrying materials, and another word for them

Answer 19

erythrocytes; no mitochondria/nucleus, have haemoglobin, flexible; biconcave disc shape, thin and
flat to increase surface area

Question 20

red vs white blood cells

Answer 20

• 7.5 vs 12-15 micrometre diameter
• no nucleus vs with nucleus
• 4.2-6.2 mil vs 5000-10,000 per mm cubed blood

Question 21

adaptation of motor neurons to transfer impulses

Answer 21

long and thin axons, extends to 1 m

Question 22

how does the proximal convoluted tubule in the kidney increase its surface area to volume ratio?

Answer 22

mivrovilli: closely packed, cube-shaped protrusions making up brush border

Question 23

structures of nephrons

Answer 23

1. proximal convoluted tubule reabsorbs nutrients/water from blood
2. renal corpuscle absorbs fluids
3. filtering component reabsorbs fluids, ion secretion
4. collecting duct final reabsorption of water to form urine

Question 24

types of cells making up alveolar epithelial tissue

Answer 24

1. type 1 (95%): long and flat for surface area; shares basement membrane with endothelium of lung capillaries, smaller diffusion distance
2. type 2 (5%): cuboid, with microvilli, lamellar bodies (vesicles) secrete pulmonary surfactant that decreases surface tension and lubricates, preventing alveoli sticking together
3. macrophages (white blood cells): endocytosis to remove toxins

Question 25

adaptations of skeletal muscle for movement

Answer 25

voluntary, cylindrical, multinucleated, membrane capable of impulse propagation, made of myofibrils made of sacromeres that can shorten

Question 26

adaptations of cardiac muscle for rapid contractions

Answer 26

involuntary, single-nucleated, made of myofibrils, branched and connected by intercalated discs allowing rapid transmission of electrical impulses

Question 27

what makes skeletal muscle cells unique from other cells?

Answer 27

larger and multinucleate, grow by joining with existing fibres rather than mitosis, doesn’t undergo apoptosis when damaged

Question 28

structure of sperm cell

Answer 28

head with nucleus and acrosome, middle with mitochondria, flagellum (axoneme)

Question 29

structure of ovum

Answer 29

nucleus, most organelles present, cortical granules, lipid drops for energy for embryo, plasma membrane, zona pellucida