Cells and Tissues

Frage	Antworten
What is a cell?	The smallest structural and functional unit of an organism.
What is the structure of the plasma membrane?	The plasma membrane consists of a lipid bilayer, 2 layers of phospholipids. These phospholipids have a hydrophilic head and a hydrophobic tail. This lipid bilayer has selective permeability, therefore it can choose what it does and does not let into the cell.
What is the function of the plasma membrane?	-Ensure cell structural integrity -Regulates entry & exit of substances -Maintains chemical composition of cytoplasm & extracellular fluid -Participates in cellular communication -Forms a cellular identification system -Participates in some enzymatic activties
What is the difference between a prokaryote and a eukaryote>	Prokaryote: smaller, no nucleus, no membrane-bound organelle, no cytoplasm, single circular DNA, divides by binary fission Eukaryote: larger, has nucleus, has membrane-bound organelle, has chromosomes, divides by mitosis
What is the structure and function of the nucleus?	Most prominent feature of cell Structure: tightly condensed chromatin. (tightly packed=heterochromatin-inactive cells. loosely packed=euchromatin-active cells) Function: cellular regulation-holds DNA, synthesis of ribosomes-in nucleolus, makes rRNA and subunits
What is the structure and function of cytoplasm?	Fluid portion that surrounds organelles Mostly water, remainder is molecules and nutrients required by cell
What is the structure and function of the golgi body?	Small flattened membranous sacs Proteins synthesised on RER pass through the golgi body
What is the structure and function of lysosomes?	Membrane encolsed vesicles formed from golgi body Break down molecules, digestion, recycle worn out cell parts
What is the structure and function of mitochondria?	Site of ATP production Double membraned organelle
What is the structure and function of the endoplasmic reticulum?	RER: studded with ribosomes, synthesizes proteins for processing and sorting SER: no ribosomes, contains enzymes that synthesize fatty acids and steroids
How does the nucleus help maintain homeostasis?	Holds genetic material which directs all cellular activities and regulates cellular structure.
What is the structure and function of the nucleolus?	Round body inside nucleus Makes ribosomal subunits from proteins and RNA called rRNA
What is transcription?	The process of making an RNA copy of a gene sequence - mRNA mRNA leaves the cell nucleus and enters the cytoplasm where it directs protein synthesis.
What is translation?	The mRNA is translated to a sequence of amino acids during protein synthesis.
What is the structure and function of cilia?	Short, hairlike projections extending from surface of cell Move fluid along cell surface
What is the structure and function of flagella?	Longer hairlike projections extending from surface of cell Move entire cell
What is the structure and function of microvilli?	Microscopic cellular protrusions that increase surface area of cells.
What is cell polarity?	Differences in shape, structure and function of cells.
What are the four types of tissues in the human body and what is their function?	Epithelial tissue: covers surfaces, lines cavities, forms glands Connective tissue: supports and protects other tissues Muscle tissue: causes movement Nervous tissue: receives and generates nerve impulses
What is the difference between simple and stratified cells?	Simple: single cell- facilitates transfer between different environments. Easier to get across Stratified: many cells-protective barrier function
What is the location, structure and function of simple squamous epithelium?	Most delicate type of epithelium Found in protected regions where absorption or diffusion occurs, where a slick, slippery surface reduces friction. e.g. internally More efficient therefore absorption and diffusion EXAMPLE: endothelium lining heart and blood vessels
What is the location, structure and function of stratified squamous epithelium?	Where mechanical and chemical stress is severe. e.g. lines regions of gut. In exposed body surfaces where mechanical and dehydration are key issues - keratinised tissue e.g. skin
What is the location, structure and function of cuboidal epithelium?	Simple: lines exocrine glands and ducts. Found in kidneys. Squamous: very rare because don't want to secrete across multiple layers. Sweat and mammary glands.
What is the location, structure and function of transitional epithelium?	Unusual stratified epithelium. Found where repeated cycles of stretching and recoiling occur. e.g. bladder
What is the location, structure and function of columnar epithelium?	Simple: Found lining stomach, intestine, gall-bladder and uterine tubes. May have microvilli or cilia to increase SA = more diffusion and absorption Stratified: rare due to diffusion and absorption. Found in large ducts e.g. salivary gland
What is the location, structure and function of glandular epithelium?	Specialized for secretion. Collections of epithelial cells that produce secretions are called glands. Exocrine: release secretions into ducts opening onto epithelial surface Endocrine: release secretions into interstitial fluid
What is the structure and function of cells of connective tissue?	To synthesis, store and defend. Structural cells: synthesis and store Immature cells: blasts. synthesis and secrete ECM and divide & differentiate into mature cells Mature cells: cytes. caretaker cells Adipocytes: fat cells and store lipid Defence cells: protect body against invasion. e.g. macrophages, mast cells, white blood cells
What is the structure and function of fibres of connective tissue?	Collagen: provide strength Reticular: provide net-like framework Elastic: provide strength and elasticity
What is the structure and function of m matrix of connective tissue?	Amorphous Ground Substance Found between cells and fibres Fluid (blood), semi fluid (cartilage), gelatinous (most others), hard (bone), secure CT cells & fibres within ECM Provide medium for substance exchange
What are the properties of connective tissue?	More extracellular matrix than cells. CT= cells and matrix (ECM) ECM= ground substance and fibres CT function is determined by properties of ECM
What are the classifications of connective tissue?	Loose connective tissue have more cells than fibres Areolar connective tissue Reticular connective tissue Adipose connective tissue Dense connective tissue have more fibres than cells Dense regular connective tissue has fibres which run in parallel Dense irregular connective tissue has fibres which run in all directions
What are the three types of muscle tissue?	Cardiac, smooth and skeletal.
Describe nervous tissue.	Main component of the brain and spinal cord in nervous system. Composed of neurons which receive and transmit impulses and neuroglia which assist nerve impulses and provide nutrients to neuron.

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