Cell Structures and Functions PDF

CELL STRUCTURES Crenation – cell shrinking AND FUNCTIONS Carrier-Mediated Transport Mechanisms Carrier-mediated transport – movement of a...

CELL STRUCTURES Crenation – cell shrinking AND FUNCTIONS Carrier-Mediated Transport Mechanisms Carrier-mediated transport – movement of a substance Cell Structure Cell – basic unit of life across a membrane by means of a carrier molecule Organelles – specialized structures Facilitated diffusion – moves substances from a higher to lower concentration; does not require ATP 1. Nucleus – contains genetic material Active transport – moves substances from a lower to 2. Cytoplasm – living material higher concentration; requires ATP Ø Cystic fibrosis – genetic disorder that affects the 3. Plasma membrane – encloses the cytoplasm and active transport of Cl- into cells nucleus Secondary active transport – moving concentration Functions of the Cell (CSCR) gradient to move another substance 1. Cell metabolism and energy use. Ø Cotransport – same direction 2. Synthesis of molecules. Ø Countertransport – opposite direction 3. Communication. 4. Reproduction and inheritance. Endocytosis and Exocytosis Endocytosis – movement of materials into cells by Cell Membrane formation of vesicles § Outer boundary of the cell Ø Phagocytosis – cell eating; solid particles are § Determines what enters and leaves the cell ingested Ø Pinocytosis – cell drinking; smaller vesicles are Extracellular – substances outside the cell formed and contains liquid Intracellular – substances inside the cell Exocytosis – secretion of materials from cells Fluid-Mosaic Model – arrangement of molecules in the Organelles cell membrane Nucleus Nuclear envelope – two-layered membrane that bounds Selectively permeable – allows some substances to pass the nucleus into or out of the cells Nuclear pores – where materials can can pass into or out Movement Through the Cell Membrane the nucleus Diffusion § Movement of a solute from an area of higher to Chromatin – loosely coiled chromosomes lower concentration gradient Nucleoli – consists of ribosomal RNA and proteins Concentration gradient – difference in the concentration of a solute in a solvent minus the concentration of the Ribosomes solute at another point § Site of protein synthesis Leak channels – allow ions to pass through Endoplasmic Reticulum § Forms tubules/sacs throughout the cell Gated channels – limit the movement of ions across the membrane Rough E.R. – protein synthesis and modification; contains ribosomes Osmosis § Diffusion of water across a selectively Smooth E.R. – lipid synthesis, detoxification, and Ca permeable membrane storage Osmotic pressure – force required to prevent movement Golgi Apparatus of water across a selectively permeable membrane § Modifies, packages, and distributes lipids and proteins Hypotonic – lower concentration Secretory vesicles Isotonic – same concentration § Transports and stores materials within cells Hypertonic – higher concentration Lysosomes § Membrane bound sacs containing hydrolytic Lysis – when cells swell, then ruptures enzymes M o r a n o , M. A. Peroxisomes Two Phases of the Cell Life Cycle § Enzymes that digest fatty acids and amino acids 1. Interphase – non-dividing phase § Enzymes that catalyze the breakdown of 2. Cell Division – formation of daughter cells from hydrogen peroxide a single parent cell Proteasomes 46 Chromosomes – diploid no. of chromosomes § Not bound by membranes § Digest selected proteins 2 X Chromosome = Female X + Y Chromosome = Male Mitochondria § Major site of ATP production Autosomes – 22 remaining pairs of chromosomes Cytoskeleton Mitosis § Holds organelles in place; enables the cell to 1. Prophase – chromatin condenses change shape 2. Metaphase – chromosomes align at the center § Microtubules – support the cytoplasm; assist in 3. Anaphase – chromatids separate at the cell division centromere and migrate to opposite poles Microfilaments – involved in cell movement 4. Telophase – chromosomes unravel to become chromatin Intermediate filaments – provide mechanical support Differentiation Centrioles Centrosome – where microtubule formation occurs § Cells develop specialized structures and functions Centrioles – specialized zone of the cytoplasm Apoptosis Spindle fibers – involved in separation of chromosome § Programmed cell death during mitosis Cellular Aspects of Aging Cillia, Flagella, and Microvilli 1. Cellular clock. Cilia – moves substances over the surface 2. Death genes. 3. DNA damage. Flagella – propel sperm cells 4. Free radicals. 5. Mitochondrial damage. Microvilli – increase the surface area of cells; aids in absorption Whole-Cell Activity Gene Expression Gene – sequence of nucleotides Transcription – making a copy of a gene Messenger RNA (mRNA) – the copy itself Codons – groups of three nucleotides Translation – converting that copied information into a protein Translation RNA (tRNA) – carry the amino acids Anti-codon – series of three nucleotides of tRNA Nucleotide Pairs Cytosine Guanine Thymine Adenine Uracil Adenine UAA – stop codon Cell Life Cycle M o r a n o , M. A.