Biology 2.6 - cell organisation

What cells differentiate from bone marrow cells

Erythrocytes and neutrophils

Shape of erythrocytes and the function

large SA:V ratio - oxygen can diffuse across their membranes, few organelles and no nucleus - space for haemoglobin, biconcave shape - increases SA:V, flexible - fit through narrow capillaries

Function and shape of neutrophils

Job is to ingest bacteria and fungi by phagocytosis, attracted to and travel towards infection sites by chemotaxis, large and have a lobed nucleus - can fit through gaps

Function and specialisation of sperm cells

fertilise egg cell, long and thin to be streamlined, haploid nucleus for fertilisation, acrosome with digestive enzymes, lots of mitochondria

Where are epithelial cells found

Alveoli, capillaires, intestines

Different functions of epithelial cells

Ciliated - have cilia that increase surface area and waft, squamous - flattened and thin to reduce diffusion distance

Adaptations of palisade cell

Many chloroplasts, long and cylindrical - pack closely but air in between for CO2 to move around, large vacuole - pushes chloroplasts to the edge of the cell (reducing diffusion distance), well developed cytoskeleton - chloroplasts can be moved by motor proteins

Process of opening the stomata by guard cell

Light energy produces ATP, potassium ions actively transported using ATP into guard cells - reduces WP, guard cells then take on water by osmosis, swell and the thickened cell wall remains rigid so gap enlarges

Adaptions of guard cell

Thickened cell wall

Four main types of tissue

Epithelial, connective, muscle, nervous

Where is epithelial tissue found

skin, digestive and respiratory systems, blood and heart chambers, walls of organs

5 functions of epithelial tissue

protection, absorption, filtration, excretion and secretion

Adaptions of epithelial tissue

no blood vessels, can have cilia and microvilli, bound close together by lateral contracts (tight junctions and desmosomes), short cell cycles to replace worn or damaged tissue.

examples where connective tissue is found

blood, bone, cartilage, tendons, ligaments

Structure of connective tissue

Non-living extracellular matrix made of proteins (collagen and elastin) and polysaccharides. Cells within connective tissue need to have the matrix as it separates the cells and enables it to withstand forces

Name of and function of immature cells in cartilage

Chondroplasts - divide by mitosis and secrete extracellular matrix

Name and function of mature cells in cartilage

chondrocytes - maintain the matrix and are less active

three types of cartilage

hyaline, fibrous, elastic

Hyaline cartilage

forms embryonic skeleton, found in the end of long bones, nose, trachea, larynx

Fibrous cartilage

found in discs between vertebrae in backbone and knee joint

Elastic cartilage

outer ear and the epiglottis

Function of muscle tissue and adaptations

provides movement, muscle cells called fibres are elongated and have special organelles called myofilaments - allow muscle fibres to contract

what are myofilaments made of

actin and myosin

three types of muscle tissue and their function

skeletal - joined to bones by tendons, move the bones by contracting, cardiac - walls of the heart, pump and move blood, smooth - wall of intestine, blood vessels, uterus, urinary tracts - propels substances

how are xylem differentiated from meristems

differentiation, cell elongation, lignification, cell is killed, end of cells break down to form continuous column

how are phloem differentiated from meristems

sieve tubes differentiated, lost most of organelles, sieve plates develop between them. companion cells keep organelles and continue metabolic processes.

stem cells purpose

renewing source of undifferentiated cells