Cell Growth SN 100 BScN (2023-2024) PDF

SN 100 BScN (2023-2024) Cell Growth: Allen, C. & Harper, V., (2020). Laboratory manual for anatomy & physiology (LL) (7th ed.). John Wiley & Sons, Canada. ISBN: 9781119662556. Tortora, G. & Derrickson, B. (2020). Principles of anatomy and physiology (16th ed.). Joh...

SN 100 BScN (2023-2024) Cell Growth: Allen, C. & Harper, V., (2020). Laboratory manual for anatomy & physiology (LL) (7th ed.). John Wiley & Sons, Canada. ISBN: 9781119662556. Tortora, G. & Derrickson, B. (2020). Principles of anatomy and physiology (16th ed.). John Wiley & Sons, Canada. ISBN: 9781119662686. Tortora, G. & Derrickson, B. (2020). Principles of anatomy and physiology (LL) (16th ed. Incorporated). John Wiley & Sons, Canada. ISBN: 9781119662792. Learning Outcomes: 1.5, 2.3 , 2.5,4.1 Growth and Reproduction of Cells l Cell growth and reproduction of cells are the most fundamental of all living functions and together constitute the cell life cycle Ø Cell growth—depends on using genetic information in DNA to make the structural and functional proteins needed for cell survival Ø Cell reproduction—ensures that genetic information is passed from one generation to the next 2 3 Protein Synthesis Ribonucleic acid (RNA) Noncoding RNA—rRna and tRNA, which are Coding RNA—mRNA, which is a transcript of each copies of a DNA gene but regulate a code for one polypeptide processes rather than code for a polypeptide Transcription—mRNA forms along a segment of one strand of DNA 4 5  l Editing the transcript Ø Noncoding introns are removed and the remaining exons are spliced together to form the final, edited version of the mRNA copy of the DNA segment Protein Spliceosomes are ribosome-sized Synthesis Ø structures in the nucleus that splice mRNA transcripts 6 7 Protein Synthesis l Translation Ø After leaving the nucleus and being edited, mRNA associates with a ribosome in the cytoplasm Ø tRNA molecules bring specific amino acids to the mRNA at the ribosome; the type of amino acid is determined by the fit of a specific tRNA’s anticodon with mRNA’s codon Ø As amino acids are brought into place, peptide bonds join them—eventually producing an entire polypeptide chain Ø Translation of genes can be inhibited by RNA interference (RNAi), which protects the cell against viral infection 8 9 10  l Processing—chaperone molecules and other enzymes in the cytosol, ER, and Golgi apparatus help polypeptides fold and then possibly combine into larger Protein protein molecules or hybrid molecules Proteome Synthesis l Ø All the proteins synthesized by a cell make up the cell's proteome Ø All the proteins synthesized in the whole body is called the human proteome 11 Cell Growth l Newly formed cells produce a variety of molecules and other structures necessary for growth by using the information contained in the genes of DNA molecules; this stage is known as interphase 12 13 Cell Growth l Production of cytoplasm Ø More cell material is made, a largely anabolic process Ø Growth and/or replication of organelles and plasma membrane Ø Replication of centrosomes and DNA in anticipation of cell division 14 Cell Growth l DNA replication Ø Replication of the genome prepares the cell for reproduction; the mechanics are similar to RNA synthesis 15 Cell Growth l DNA replication (cont) Ø DNA base pairing l The DNA strand uncoils and the strands come apart l Along each separate strand, a complementary strand forms Ø Because the strands are rebuilt in opposite directions, one strand is not completely rebuilt Ø Telomeres are noncoding, protective segments of DNA at the ends of a chromosome; they are used up during DNA replication to prevent loss of needed DNA code; telomeres can be rebuilt by the enzyme telomerase 16 17 Cell Growth Ø DNA base pairing (cont) The two new strands are called chromatids of chromosomes Chromatids are attached pairs; the point of attachment is called the centromere 18 Cell Growth l The growth phase of the cell life cycle can be subdivided into the first growth phase (G1), the [DNA] synthesis phase (S), and the second growth phase (G2) 19 Cell Reproduction l Cells reproduce by splitting themselves into two smaller daughter cells 20 Cell Reproduction l Mitotic cell division—the process of organizing and distributing nuclear DNA during cell division has four distinct phases Ø Prophase--”before phase” l After the cell has prepared for reproduction during interphase, the nuclear envelope falls apart as the chromatids coil up to form chromosomes that are joined at the centromere (Figure 5-9) l As chromosomes form, centrosomes (centrioles/aster) move away from each other toward the poles of the parent cell and spindle fibers are constructed between them 21 22 Cell Reproduction l Mitotic cell division (cont) Ø Anaphase-- “apart phase” l The centromere of each chromosome splits to form two chromosomes, each consisting of a single DNA molecule l Each chromosome is pulled toward the nearest pole to form two separate, but identical, pools of genetic information 23 Cell Reproduction l Mitotic cell division (cont) Ø Telophase-- “end phase” l DNA returns to its original form and location within the cell l After completion of telophase, each daughter cell begins interphase to develop into a mature cell 24 25 Regulating the Cell Life Cycle l Cyclin-dependent kinases (CDKs) are activating enzymes that drive the cell through the phases of its life cycle l Cyclins are regulatory proteins that control the CDKs and “shift” them to start the next phase 26 Cycle of Life: Cells l Different types of cells have different life cycles l Advancing age creates changes in cell numbers and in their ability to function effectively Ø Examples of decreased functional ability include muscle atrophy, loss of elasticity of the skin, and changes in the cardiovascular, respiratory, and skeletal systems 27 The Big Picture: Cell Physiology and the Whole Body l Most cell processes are occurring at the same time in all of the cells throughout the body l The processes of normal cell function result from the coordination dictated by the genetic code. 28 SN 200 BScN (2023-2024) Cell Division/Mitosis: Questions?