Girls Records 5/24/2019 Chapter 3 The Cell

Cell Structure Review Cell Membrane property/gate September

Cell Membrane Review Composition Proteins Carbohydrates Lipids September

Structure of Cytoplasm definition: the material btw the plasma membrane and the nuclear membrane September

Cytosol gel-like; fluid portion of the cytoplasm, intracellular fluid September

Cytosol Contents higher potassium, lower sodium concentrations (the opposite is found in extracellular fluid!), more dissolved proteins, less carbohydrates, some amino acids and lipids September

Cytosol Contents insoluble material: inclusions include nutrients and lipid droplets September

Organelles: Cytoplasm Contents “little organs” intracellular structure that performs a specific function or group of functions September

Cytoskeleton definition: a protein framework of microtubules & microfilaments functions: strength and flexibility September

Microfilaments thinnest composed of protein actin attach plasma membrane to underlying cytoplasm September

Intermediate Filaments intermediate in size protein composition varies function for strength and stability some specialized like keratin fibers in superficial layers of skin for strength September

Microtubules microscopic hollow tubules of globular protein tubulin function for strength and rigidity found in cilia, flagella, centrioles, and spindle fibers September

Microvilli small finger-like extensions of the exposed plasma membrane of an epithelial cell function to increase surface area for absorption September

Centrioles [aka centrosomes] cylindrical composed of 9 groups of microtubules (3 in each group) functions in mitosis/meiosis by organizing the microtubules of the spindle apparatus some cells lack these, hence no dividing September

Cilium (cilia p) slender extending above free surface anchored by basal bodies undergoes cycles of mvmt. composed of microtubules September

Flagellum [ flagella p ] structurally similar to cilium used to propel cell through fluid only human example: sperm September

(g) Ribosomes contains rRNA & proteins protein-making machines !! free : scattered fixed : attached September

Proteosomes aka proteases hollow, cylindrical protein breaking enzymes function in removal and recycling damaged or denatured proteins and breaking down abnormal proteins such as those produced w/ in cells infected by viruses September

Endoplasmic Reticulum channels intracellular transportation SER:free ribosomes RER: fixed ribosomes ER the grand canal Rough Smooth September

Golgi body (flattened sacs) modification & packaging “recycling plant” Girls Records 5/24/2019 Golgi body (flattened sacs) modification & packaging “recycling plant” Aka: golgi apparatus September

Lysosomes known as cellular suicide package lysosomal membranes disintegrate releasing enzymes autolysis September

Peroxisomes smaller carry different enzymes generate H2O2 in process free radical: ion or molecules containing unpaired e- may enter into destructive reactions September

Mitochondria [aka mitochondrion s ] generates ATP = energy # varies depending on energy needs of cell reaction sequence is glycolysis if O2  aerobic metabolism or cellular respiration produces about 95% of cell’s energy needs September

Mitochondrion September

Any Questions ?? September

The Structure of the Nucleus Coming Next: The Structure of the Nucleus September

Cell Structure Review September

Cell Structure Review September

Structure of Nucleus contains DNA, RNA, and proteins functions as control center for cellular activity September

Structure of Nucleus cont’ Nucleolus: dense region in nucleus that represents the site of rRNA (ribosomal) synthesis Nuclear envelope: double membrane surrounding the nucleus Nucleoplasm: fluid contents Nuclear pores: permit mvmt. Of material btw nucleus and cytosol September

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Chromosomes dense structures composed of tightly coiled DNA strands associated w/ histones (special protein that guards the activity of each gene) become visible in the nucleus when a cell prepares to undergo mitosis /meiosis Human somatic cells contain 46 September

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Chromatin loosely coiled tangle of fine filaments in a cell not dividing that condenses in a dividing cell September

Information Storage Genetic code: chemical language (sequencing of amino acids) of cell to construct proteins single DNA molecule: pair of DNA strands, H bonds btw complementary N-bases info in sequence of bases (A,T,C,G) in triplet code for amino acid Ex: ACA = cysteine September

Information Storage cont’ Gene: functional unit of heredity has all triplets needed to produce specific proteins, or tRNA or rRNA promoter or control segment: special region of DNA for regulating gene activity September

Protein Synthesis Where are the ribosomes? genes? Transcription: the encoding of genetic instructions on a strand of mRNA mRNA = messenger RNA is a transcript (copy) of info in the gene September

Protein Synthesis cont’ RNA polymerase binds to promoter of gene synthesizing mRNA strand RNA bases: A,C,G, and uracil (U) codon: sequence of 3-Nbases along an mRNA strand that will specify the location of a single amino acid in a peptide chain September

Protein Synthesis cont’ Translation: the process of peptide formation using the information from mRNA begins when synthesized mRNA leaves nucleus and binds w/ a ribosome in cytoplasm tRNA = transfer RNA delivers amino acids to be used by ribosome to assemble protein September

Protein Synthesis cont’ more than 20 types of tRNA anticodon: triplet of N-bases on a tRNA molecule that interacts w/ an appropriate codon on a strand of mRNA takes about 20 seconds to produce a typical protein! September

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