Title [ Q1W4 ] General Biology Transes.pdf ✅

CHAPTER 4 : THE CELL CYCLE Introduction to Cell Division, Mitosis in Humans, Plants, and Prokaryotes GBIO I S.Y. ‘23-24 SHS STEM S1Q1 WEEK 4 | CAMPBELL BIOLOGY 8TH ED. | CAMPBELL & REECE 04 THE CELL CYCLE PPT & LECTURE CAMPBELL BIO 04 1.0 KEY ROLES OF CELL DIVISION ● The ability of organisms to reproduce best distinguishes living things from nonliving matter. ● The continuity of life is based on the reproduction of cells, or cell division. 1.1 UNICELLULAR VS. MULTICELLULAR CELL DIVISION UNICELLULAR VS. MULTICELLULAR ORGANISMS UNICELLULAR MULTICELLULAR Division of one cell reproduces the entire organism Multicellular organisms depend on cell division for: (1) Reproduction, (2) Growth, (3) Repair Injury of the cell can cause serious injury/death Other cells can replace the injury/death of a cell 2.0 GENETICALLY IDENTICAL DAUGHTER CELLS ● Most cell division results in daughter cells with identical genetic information, DNA. ● A special type of division produces nonidentical daughter cells (gametes, or sperm and egg cells). 2.1 CELLULAR ORGANIZATION OF THE GENETIC MATERIAL ● DNA: Deoxyribonucleic Acid ● Approximate size of DNA in humans: 2 meters ● All the DNA in a cell constitutes the cell’s genome. - A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells) ● DNA molecules in a cell are packaged into chromosomes. QUESTION 2.1. Cellular Organization of DNA Since the DNA is 2 meters, and the typical size of eukaryotic cells are 10-100 micrometers, how will the DNA strands enter and fit that small cell? ● This will be done by coiling the DNA material into chromosomes to package and compress the DNA in an organized and wavy pattern. ● This means that chromosome = coiled DNA. ● Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus. TYPES OF CELL ACCORDING TO REPRODUCTION Somatic / Body Cells ● Nonreproductive cells ● Have two sets of chromosomes ● 46 genetically identical cells ● Diploid (2n) Gametes / Sex Cells ● Reproductive cells: sperm and egg ● Have half as many chromosomes as somatic cell ● 23 from the father’s sperm cell, and 23 from the mother’s egg cell, ● Haploid (n) 3.0 DISTRIBUTION OF CHROMOSOMES DURING EUKARYOTIC CELL DIVISION ● In preparation for cell division, DNA is replicated and the chromosomes condense. ● Here is the process of how DNA develops into chromosomes before the cell division: 1. DNA 2. Chromatin 3. Chromosome WONRIKA ON X | SHS STEM NOTES | CAMPBELL BIO 8TH ED. GENERAL BIOLOGY I SEM1 Q1 PAGE 1
CHAPTER 4 : THE CELL CYCLE Introduction to Cell Division, Mitosis in Humans, Plants, and Prokaryotes GBIO I S.Y. ‘23-24 SHS STEM S1Q1 WEEK 4 | CAMPBELL BIOLOGY 8TH ED. | CAMPBELL & REECE 4. Duplicated Chromosomes 5. Sister Chromatids DISTRIBUTION OF CHROMOSOMES DNA ● Two-meter genetic material. Chromatin ● Thread-like and wavy structure of the DNA which is formed to fit the cell’s nucleus. Chromosome ● To prepare for the cell division, the chromatin condenses into a chromosome. ● A chromosome is a coiled chromatin structure. Duplicated Chromosomes ● In preparation for cell division, the chromosome, which contains DNA, is replicated into a duplicated chromosome. Sister Chromatids ● Each duplicated chromosome has two sister chromatids, which separate during cell division. ● Centromere: refers to the narrow waist of the duplicated chromosome, where the two chromatids are most closely attached. 4.0 TYPES OF CELL DIVISION ● There are two types of cell division: 1. Mitosis 2. Meiosis DISTRIBUTION OF CHROMOSOMES MITOSIS MEIOSIS Produces Identical daughter cells Non-identical daughter cells Chromosomal Content Diploid (2n) Haploid (n) Type of eukaryotic human cell Somatic / Body Cell Gamete / Sex Cell Purpose Growth, development, and repair Reproduction 4.1 MITOSIS ● Eukaryotic cell division which produces identical daughter cells (Mitotic division) consists of: 1. Mitosis: division of the nucleus 2. Cytokinesis: division of the cytoplasm 4.2 PHASES OF THE CELL CYCLE ● The overall cell cycle consists of: 1. Mitotic (M) phase: mitosis and cytokinesis 2. Interphase: cell growth and copying of chromosomes in preparation for cell division 5.0 INTERPHASE ● Interphase (about 90% of the cell cycle) can be divided into subphases: a. G1 phase (“first gap”) b. S phase (“synthesis”) c. G2 phase (“second gap”) ● The cell grows during all three phases, but chromosomes are duplicated only during the S phase. SUBPHASES OF THE INTERPHASE G1 Phase ● RNA and protein synthesis ● Cell size increases ● Carry out normal cell function S Phase ● DNA replication ● Chromosomes are duplicated ● Centrosomes are duplicated G2 Phase ● Duplication of organelles ● Energy replenishment ● Dismantling of the cytoskeleton WONRIKA ON X | SHS STEM NOTES | CAMPBELL BIO 8TH ED. GENERAL BIOLOGY I SEM1 Q1 PAGE 2
CHAPTER 4 : THE CELL CYCLE Introduction to Cell Division, Mitosis in Humans, Plants, and Prokaryotes GBIO I S.Y. ‘23-24 SHS STEM S1Q1 WEEK 4 | CAMPBELL BIOLOGY 8TH ED. | CAMPBELL & REECE G0 (GAP ZERO) - CELL CYCLE ARREST ● Quiescent stage ● Applies to cells that do not do repetitive cell division. ● Examples: 1. Nerve Cells 2. Cardiac Cells - Hence, a person who encounters a nerve/brain injury, and/or a heart defect, are in a critical condition and may have little chances of recovering again. 6.0 MITOSIS ● Mitosis is conventionally divided into five phases: 1. Prophase 2. Prometaphase 3. Metaphase 4. Anaphase 5. Telophase ● Cytokinesis is well underway by late telophase. WONRIKA ON X | SHS STEM NOTES | CAMPBELL BIO 8TH ED. GENERAL BIOLOGY I SEM1 Q1 PAGE 3
CHAPTER 4 : THE CELL CYCLE Introduction to Cell Division, Mitosis in Humans, Plants, and Prokaryotes GBIO I S.Y. ‘23-24 SHS STEM S1Q1 WEEK 4 | CAMPBELL BIOLOGY 8TH ED. | CAMPBELL & REECE SUMMARY OF THE MITOTIC CELL DIVISION (MITOSIS) PHASE CENTROMERE GENETIC MATERIAL NUCLEOLUS NUCLEAR MEMBRANE CELL SHAPE G2 of Interphase Doubled during S Phase Chromatin structure; duplicated during S phase Present Present Circular Prophase Starting to move away to form mitotic spindle; release microtubules Chromatin transforms into chromosomes, which consists of sister chromatids attached to a centromere. Absent Present Circular Prometaphase Now located at opposite poles of cell; longer microtubules, some of which attach to the centromere — called “kinetochore microtubules” Genetic material is “supercoiled” to be ready for the next part of mitosis Absent Absent Circular Metaphase Still at opposite poles of the cell; the kinetochore microtubules pull each other apart Aligned at the center, called the “metaphase plate” Absent Absent Circular Anaphase Kinetochore microtubules pull the sister chromatids back and forth, until the sister chromatids separate Separated Absent Absent Elongated,due to the nonkinetochore microtubules continually growing which elongates the cell Telophase The centromeres returned their mitotic spindle; there will be one (1) centrosome for each cell Separated chromosomes is distributed to their respective cell area; chromosomes transform back into chromain Already forming Already forming The elongated cell results into two circular daughter cells;this is due to a contractile ring of microfilaments, called the “cleavage furrow,” forming and tightening at the center until it separates the cell. 6.0 MITOSIS IN PLANT CELLS ● In animal cells, cytokinesis occurs by a process known as cleavage, forming a cleavage furrow. ● In plant cells, a cell plate forms during cytokinesis. ● Plant cells form vesicles that contain components similar to a cell wall. - These vesicles align themselves in the metaphase plate. - It will expand in length until the cell wall & vesicles are joined together, forming a cell plate. ● This results in two new daughter cells. ● See illustration on the next page. WONRIKA ON X | SHS STEM NOTES | CAMPBELL BIO 8TH ED. GENERAL BIOLOGY I SEM1 Q1 PAGE 4