Cells structure and specialized roles

A section through a liver cell (animal cell): cell membrane nucleus controls what enters and leaves the cell contains the DNA and so controls the cell cytoplasm DNA metabolic (chemical) reactions occur here contains the coded instructions to make proteins

Section through a palisade cell of a leaf (plant cell) chloroplast cell membrane large sap vacuole nucleus cellulose cell wall cytoplasm

CELLS Vacuole Nucleus Cytoplasm Cell Wall Cell membrane Chloroplast

Red blood cells transport oxygen cytoplasm contains no nucleus cell surface membrane allows more room for haemoglobin cytoplasm contains haemoglobin haemoglobin is a protein which carries the oxygen molecules bi-concave disc shape increases surface area over which absorption of oxygen can occur

Muscle cells contract and enable movement of the body Muscle cells have many nuclei and large no: of mitochondria. nucleus cell surface membrane protein strands The strands of protein (Actin and Myosin) slide over each other making the muscle cell (fibre) shorter and causing the muscle to contract

Ciliated cells move bacteria and dust away from the lungs Cilia are small extensions of the cell. They beat rhythmically to sweep mucus, which has trapped bacteria and dust, away from the lungs nucleus magnification X3000

Xylem vessels transport water and minerals up the plant xylem vessels are continuous tubes xylem vessel no cytoplasm hollow: allows for continuous flow of water and dissolved mineral ions lignin water-proof and strong; helps support the plant longitudinal section cross-section

Root hair cells absorb minerals and water from the soil Cross-section of a root hair cell cell membrane semi-permeable, so will allow water and mineral ions into the cell cytoplasm contains no chloroplasts as no photosynthesis is needed root hair cell increases surface area for absorption of water and mineral ions

CELLS Vacuole Nucleus Cytoplasm Cell Wall Cell membrane Chloroplast

All cells have these features in common: a nucleus contains genetic material which controls the cell's behaviour. cytoplasm where chemical processes (controlled by enzymes) take place a cell membrane which controls what passes into and out of the cell In addition, plant cells have the following unique features: a rigid cell wall made of cellulose to strengthen the cell vacuoles to store cell sap chloroplasts contain chlorophyll which enables photosynthesis to take place.