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Cells and Tissues
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A human Karyotype
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Chromosome, DNA, Genes
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Protein Synthesis Gene—DNA segment that carries a blueprint for building one protein Proteins have many functions Building materials for cells Act as enzymes (biological catalysts) RNA is essential for protein synthesis
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Role of RNA Transfer RNA (tRNA)
Transfers appropriate amino acids to the ribosome for building the protein Ribosomal RNA (rRNA) Helps form the ribosomes where proteins are built Messenger RNA (mRNA) Carries the instructions for building a protein from the nucleus to the ribosome
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Types of RNA
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Transcription and Translation
Transfer of information from DNA’s base sequence to the complimentary base sequence of mRNA Three-base sequences on mRNA are called codons
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Transcription
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Transcription and Translation
Base sequence of nucleic acid is translated to an amino acid sequence Amino acids are the building blocks of proteins
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Transcription and Translation
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Nucleus (site of transcription) Cytoplasm (site of translation
Protein Synthesis Nucleus (site of transcription) DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Synthetase enzyme Amino acids Cytoplasm (site of translation ) Correct amino acid attached to each species of tRNA by an enzyme Growing polypeptide chain Nuclear pore Nuclear membrane mRNA As the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid Direction of ribosome advance; ribosome moves the mRNA strand along sequentially as each codon is read Small ribosomal subunit Portion of mRNA already translated tRNA “head” bearing anticodon Large ribosomal subunit Peptide bond Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon Codon Ala Phe Ser Gly Met C G U A Figure 3.16
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template Cytoplasm (site of translation ) Nuclear pore Nuclear membrane mRNA Figure 3.16, step 1
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Cytoplasm (site of translation ) Nuclear pore Nuclear membrane mRNA Small ribosomal subunit Large ribosomal subunit Codon U G C A Figure 3.16, step 2
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Synthetase enzyme Amino acids Cytoplasm (site of translation ) Correct amino acid attached to each species of tRNA by an enzyme Nuclear pore Nuclear membrane mRNA Small ribosomal subunit Large ribosomal subunit Codon U G C A Figure 3.16, step 3
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Synthetase enzyme Amino acids Cytoplasm (site of translation ) Correct amino acid attached to each species of tRNA by an enzyme Nuclear pore Nuclear membrane mRNA Small ribosomal subunit tRNA “head” bearing anticodon Large ribosomal subunit Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon Codon U G C A Figure 3.16, step 4
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Synthetase enzyme Amino acids Cytoplasm (site of translation ) Correct amino acid attached to each species of tRNA by an enzyme Growing polypeptide chain Nuclear pore Nuclear membrane mRNA As the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain Direction of ribosome advance; ribosome moves the mRNA strand along sequentially as each codon is read Small ribosomal subunit tRNA “head” bearing anticodon Large ribosomal subunit Peptide bond Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon Codon Ala Phe Ser Gly Met C G U A Figure 3.16, step 5
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Nucleus (site of transcription) Cytoplasm (site of translation
DNA mRNA specifying one polypeptide is made on DNA template mRNA leaves nucleus and attaches to ribosome, and translation begins Synthetase enzyme Amino acids Cytoplasm (site of translation ) Correct amino acid attached to each species of tRNA by an enzyme Growing polypeptide chain Nuclear pore Nuclear membrane mRNA As the ribosome moves along the mRNA, a new amino acid is added to the growing protein chain Released tRNA reenters the cytoplasmic pool, ready to be recharged with a new amino acid Direction of ribosome advance; ribosome moves the mRNA strand along sequentially as each codon is read Small ribosomal subunit Portion of mRNA already translated tRNA “head” bearing anticodon Large ribosomal subunit Peptide bond Incoming tRNA recognizes a complementary mRNA codon calling for its amino acid by binding via its anticodon to the codon Codon Ala Phe Ser Gly Met C G U A Figure 3.16, step 6
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transcription and translation
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Body Tissues Tissues Groups of cells with similar structure and function Four primary types Epithelial tissue (epithelium) Connective tissue Muscle tissue Nervous tissue
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Epithelial Tissues Locations Body coverings Body linings
Glandular tissue Functions Protection Absorption Filtration Secretion
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Epithelium Characteristics
Cells fit closely together and often form sheets The apical surface is the free surface of the tissue The lower surface of the epithelium rests on a basement membrane
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Avascular (no blood supply)
Regenerate easily if well nourished
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Epithelium Characteristics
Figure 3.17a
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Classification of Epithelia
Number of cell layers Simple—one layer Stratified —more than one layer Figure 3.17a
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Classification of Epithelia
Shape of cells Squamous flattened Cuboidal cube-shaped Columnar column-like Figure 3.17b
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Simple Epithelia Simple squamous Single layer of flat cells
Usually forms membranes Lines body cavities Lines lungs and capillaries
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Simple Epithelia Figure 3.18a
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Simple Epithelia Simple cuboidal Single layer of cube-like cells
Common in glands and their ducts Forms walls of kidney tubules Covers the ovaries
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Simple Epithelia Figure 3.18b
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Simple Epithelia Simple columnar Single layer of tall cells
Often includes mucus-producing goblet cells Lines digestive tract
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Simple Epithelia Figure 3.18c
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Simple Epithelia Pseudostratified columnar
Single layer, but some cells are shorter than others Often looks like a double layer of cells Sometimes ciliated, such as in the respiratory tract May function in absorption or secretion
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Simple Epithelia Figure 3.18d
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Stratified Epithelia Stratified squamous
Cells at the apical surface are flattened Found as a protective covering where friction is common Locations Skin Mouth Esophagus
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Stratified Epithelia Figure 3.18e
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Stratified Epithelia Stratified cuboidal —two layers of cuboidal cells
Stratified columnar —surface cells are columnar, cells underneath vary in size and shape Stratified cuboidal and columnar Rare in human body Found mainly in ducts of large glands
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Stratified Epithelia Transitional epithelium
Shape of cells depends upon the amount of stretching Lines organs of the urinary system
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Stratified Epithelia Figure 3.18f
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Glandular Epithelium Gland
One or more cells responsible for secreting a particular product
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Glandular Epithelium Two major gland types Endocrine gland
Ductless since secretions diffuse into blood vessels All secretions are hormones Exocrine gland Secretions empty through ducts to the epithelial surface Include sweat and oil glands endocrine exocrine
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