Chapter 2 _ BIOSCI2 - 2024.pdf

Chapter 2 - Cell Structures and Functions BIO. SCI. 2 - General Zoology Cristel Joy C. Mallari Instructor I Overview A. Cells as Building Blocks of Life 1. Cell membranes 2. Movement across membranes 3. Cytoplasm, Organelles and Cellular Components 4. The Nucleus as the informa...

Chapter 2 - Cell Structures and Functions BIO. SCI. 2 - General Zoology Cristel Joy C. Mallari Instructor I Overview A. Cells as Building Blocks of Life 1. Cell membranes 2. Movement across membranes 3. Cytoplasm, Organelles and Cellular Components 4. The Nucleus as the information center 5. The Cell Cycle B. Type of Cells  Protection & Support Movement Communication Animal cell Metabolism & Energy release  Robert Hooke Robert Hooke’s microscope What Hooke saw under microscope Robert Hooke’s publication (1665) Unified Cell Theory 1. Cells are the basic unit of life. 2. All living things are composed of one or more cells. 3. Cells arise from pre-existing cells through cell division Cell membrane Semi-permeable Phospholipid bi-layer Hydrophilic polar head Hydrophobic fatty acids tail studded proteins Fluid Mosaic Model Movement across membranes selectively permeable allows some materials to freely enter or leave the cell other materials cannot move freely - specialized structure, energy investment for crossing Transport mechanisms Active transport Passive transport Active Transport requires cell’s energy against CG - conc. of the substance in cytoplasm > conc. in the ECF Small molecules ions Passive Transport Passive Transport Descriptions naturally occurring Mechanism A single substance tends to move from larger molecules Diffusion an area of high concentration to an area of low concentration until the concentration is equal across a space. does not require energy Materials diffuse across the plasma moves along the CG Facilitated membrane with the help of membrane proteins. A concentration gradient exists transport that would allow these materials to Higher conc. to lower diffuse into the cell without expending cellular energy conc. Movement of water through a semipermeable membrane according to the concentration gradient of water Osmosis across the membrane, which is inversely proportional to the concentration of solutes. Other factors that affect particle movement Tonicity Osmolarity describes how an describes the total solute extracellular solution can concentration of the solution change the volume of a low osmolarity = >H2O molecules cell by affecting osmosis relative to the number of solutes Types of Solutions on which cells are exposed: Hypotonic - ECF has lower osmolarity than the cytoplasm Hypertonic - ECF has higher osmolarity than the cytoplasm Isotonic - ECF has the same osmolarity as the cell cytoplasm Cytoplasm, Organelles and Cellular Components  “microtubule-organizing center” ATP Cristae -folds Matrix Membranes Vacuoles - Storage “organelle-recycling facility” Phagocytosis, endosymbiosis  Cytoplasm Mitochondrion Ribosomes -semi-fluid/gelatinous -”energy factories” -site for protein synthesis matrix that houses other -ATP synthesis (cellular -”tiny dots” in cytoplasm organelles respiration) -attach to ER, NE, etc. -cytosol, cytoskeleton, and -cristae – folds other cellular chemicals -matrix and membranes Cytoplasm  Smooth Endoplasmic Rough Endoplasmic Golgi Apparatus/ Reticulum Reticulum Body/Complex -system of internal -studded with ribosomes -collects, packages, and membrane -carry out protein distributes molecules that -manufacture synthesis are being manufactured carbohydrates and lipids -”intracellular highway” inside the cell -calcium-ion storage and drug detoxification Cytoplasm Vesicles and Vacuoles Lysosomes Cytoskeleton -membrane-bound sacs -”organelle recycling -support and cell shape -for transport and storage facility” for cell motion -hydrolytic enzymes to -network of protein fibers destroy pathogens 1. Microfilament- cellular movement -phagocytosis & exocytosis 2. Intermediate filament- mainly structural Peroxisomes 3. Microtubules-resist -small, round, membrane- compression bound -carry out oxidation reaction for detoxification - hydrogen peroxide (H2O2) storage - Safely break down into O2 and H2O  Centrosomes Flagella Chloroplast -”microtubule organizing -long, hair-like structures -plant cell organelles that center” that extend from the carry out photosynthesis -contains a pair of plasma membrane: move 1. thylakoids stack - granum centrioles an entire cell 2. fluid - stroma -pulling the duplicated 3. Chlorophyll chromosomes to opposite Cilia ends of the dividing cell -short, hair-like structures Cell wall that are used to move -rigid covering that entire cells or substances protects, provides along the outer surface of structural support, and the cell gives shape to the cell Flagellum Cilia The Nucleus as the information center Nucleoplasm Chromatin & chromosomes Nuclear envelope Nucleopore Nucleolus  Exclusome Nitroplast -compartments/containers in mammalian -unicellular algae Braarudosphaera bigelowii cells -”nitrogen-fixing organelle” -may serve as a “genome defense system” -how the early nucleus formed The Cell Cycle series of events involving cell growth and cell division that produces two new daughter cells Interphase- cell grows and DNA is replicate Mitotic phase- replicated DNA and cytoplasmic contents are separated, and the cell divides G1 Phase (First Gap) cells’ active at the biochemical level accumulating the building blocks of chromosomal DNA and associated proteins accumulating sufficient energy reserves to complete the tasks of replicating each chromosome in the nucleus S Phase (Synthesis of DNA) DNA replication proceeds in the formation of identical pairs of DNA molecules—sister chromatids Duplicated centrosomes two centrosomes mitotic spindle (orchestrates the movement of chromosomes during mitosis) G2 Phase (Second Gap) cell replenishes its energy stores and synthesizes proteins necessary for chromosome manipulation Some cell organelles are duplicated cytoskeleton- dismantled to provide resources for the mitotic phase The Mitotic Phase multi-step process during which the duplicated chromosomes are aligned, separated, and move into two new, identical daughter cells Karyokinesis / Mitosis Cytokinesis - “cell 1. prophase motion” 2. prometaphase physical separation of the 3. metaphase cytoplasmic components 4. anaphase into the two daughter 5. telophase cells resulting in the division of the cell nucleus The Karyokinesis is divided into five stages then Cytokinesis G0 Phase Cells are not actively preparing to divide quiescent (inactive) stage that occurs when cells exit the cell cycle Some cells enter G0 temporarily until an external signal triggers the onset of G1 Other cells that never or rarely divide, such as mature cardiac muscle and nerve cells, remain in G0 permanently The Process of Meiosis Haploid cells that are part of the sexual reproductive cycle are produced by this type of cell division An animal cell with a diploid number of four (2n = 4) proceeds through the stages of meiosis to form four haploid daughter cells. Mitosis v.s. Meiosis both forms of division of the nucleus in eukaryotic cells Particulars MITOSIS MEIOSIS Division Single Double Type of Cells Body cells / Somatic cells Sex cells Ploidy Diploid - two sets of chomosomes Haploid - one set of chromosomes Outcome 2 daughter cells 4 haploid cells Type of Cells Prokaryote simple, mostly single-celled (unicellular) organisms lacks a nucleus; or any other membrane-bound organelles prokaryotic DNA is found in a central part of the cell called the nucleoid General Structure of a Prokaryote peptidoglycan cell wall and many have a polysaccharide capsule flagella - locomotion pili - material exchange fimbriae - attachment Eukaryotic cells membrane-bound nucleus numerous membrane- bound organelles “true nucleus”  This phylogenetic tree was constructed by microbiologist Carl Woese using data obtained from sequencing ribosomal RNA genes. The tree shows the separation of living organisms into three domains: Bacteria, Archaea, and Eukarya. (credit: Eric Gaba; NASA Astrobiology Institute) LUCA  Present in Present in Cell Present in Functions Prokaryotes Animal Components Plant Cell? ? Cell? Separates cell from the external environment; Plasma controls passage of organic molecules, ions, Yes Yes Yes membrane water, oxygen, and wastes into and out of the cell Provides turgor pressure to plant cells as the fluid inside the central vacuole; site of many Cytoplasm Yes Yes Yes metabolic reactions; medium inwhich organelles are found The darkened area within the nucleus where Nucleolus No, nucleoid Yes Yes ribosomal subunits are synthesized. No, but a A cell organelle that houses DNA and directs Nucleus nucleoid Yes Yes the synthesis of ribosomes and proteins region Ribosomes Protein synthesis Yes Yes Yes Mitochondria ATP production/cellularrespiration No Yes Yes Oxidizes and thus breaks down fatty acids Peroxisomes No Yes Yes and amino acids, and detoxifies poisons Vesicles and Storage and transport; digestive function in No Yes Yes vacuoles plant cells Unspecified role in cell division in animal cells; Centrosome No Yes No source of microtubules in animal cells  Digestion of macromolecules; recycling of Lysosomes No Yes No worn-out organelles Yes, Protection, structural support &maintenance Yes, Primarily Cell wall No Primarily of cell shape peptidoglycan cellulose Chloroplasts Photosynthesis No No Yes Endoplasmic Modifies proteins and synthesizes lipids No Yes Yes reticulum Modifies, sorts, tags, packages, and Golgi apparatus No Yes Yes distributes lipids and proteins Maintains cell's shape, secures organelles in specific positions, allows cytoplasm and Cytoskeleton Yes Yes Yes vesicles to move within the cell, and enables unicellular organisms to move independently Flagella Cellular locomotion Some Some No Cellular locomotion, movement of particles Cilia along the extracellular surface of the plasma Some Some No membrane, and filtration Learning Activity (Cell Analogy) Group Activity Deadline? Attendance