B2.3 Cell specialization

Question 1

Process of developing specialised cells by differentiation in fertilization

Answer 1

Multicellular organisms start as a zygote
Zygote duplicated repeatedly to form an embryo of many genetically identical cells
Cells develop along different pathways to become specialised

Question 2

Stem cell

Answer 2

Cells that can divide indefinitely and have the potential to differentiate along different pathways

Question 3

Stem cell niche

Answer 3

Precise location of stem cells within a tissue

Question 4

Totipotent stem cell

Answer 4

Can differentiate into any cell type capable of continued division

Question 5

Pluripotent

Answer 5

Can differentiate into wide range of cells, some differentiation

Question 6

Multipotent

Answer 6

Can differentiate into small range of cell types, exist throughout life of organism

Question 7

Adaptations of red blood cells to increase their SA:V ratio

Answer 7

Flattened shape maximises surface area, no nucleus allows for flattened shape and more room for oxygen

Question 8

Adaptations of proximal convoluted tubule cells in the nephron to increase their SA:V ratio

Answer 8

Microvilli greatly increase surface area available for absorption

Question 9

Adaptation of Type 1 Pneumocytes in alveoli

Answer 9

Adapted for extreme thiness to reduce distances for diffusion
Around 95% of lung surface area
Used for diffusion of oxygen and carbon dioxide

Question 10

Adaptation of Type 2 Pneumocytes in alveoli

Answer 10

Adapted to secrete surfactant onto inner surface of alveolus
Contain secretory vesicles called lamellar bodies
Dense cytoplasm with mitochondria RER and lysosomes
Vesicles secrete surfactant which reduces surface tension and prevents alveolar surfaces sticking together

Question 11

Striated muscle cell

Answer 11

Muscle connected to bones by tendons and used to generate movement of the body
Many nuclei per cell
Contractile myofibrils made of actin and myosin myofilaments
Long cylindrical shape to cause movement over long distances

Question 12

Cardiac muscle cell

Answer 12

Makes up heart
Single nucleus per cell
Contain contractile myofibrils made of actin and myosin myofilaments to enable contractions
Short branching shape for interconnected network of muscle cells

Question 13

Zygote

Answer 13

Fertilised egg cell from sperm delivering genetic material to the egg to form diploid nucleus

Question 14

Egg cell adaptations

Answer 14

External layer of glycoproteins as barrier to sperm
Cortical granules to harden zona pellucida and digest receptors
Entry surrounded by layer of small diploid follicle cells for nutrition
Many mitochondria

Question 15

Sperm cell adaptations

Answer 15

Head contains haploid nucleus to provide genetic material
Head with acrosome and enzymes to digest zona pellucida
Midpiece with mitochondria needed for movement
Tail contains axoneme microtubules for movement