Biology 5090 Topics 1-15 Flashcards

Cell Structure and Specialized Cells

• Animal Cell Structures:

  • Nucleus: Controls cell activities.

  • Ribosome: Site of protein synthesis.

  • Mitochondria: Provide energy by aerobic respiration.

  • Cytoplasm: Site of chemical reaction.

  • Cell membrane: Partially permeable; controls movement of substances in and out.

• Plant Cell Structures:

  • Cell wall: Provides structure and protection.

  • Sap vacuole: Contains cell sap to maintain cell shape.

  • Chloroplast: Contains chlorophyll to absorb light energy for photosynthesis.

• Bacterial Cell:

  • Plasmid: Contains double-stranded DNA.

  • Circular DNA: Genetic material of the bacteria.

• Specialized Animal Cells:

  • Ciliated cell: Contains cilia to move mucus.

  • Sperm cell: Male sex cell for reproduction.

  • Egg cell: Female sex cell for reproduction.

  • Nerve cell/neurone: Carries impulses.

  • Red blood cell: Carries oxygen.

• Specialized Plant Cells:

  • Root hair cell: Absorbs water and mineral ions from the soil.

  • Xylem vessel: Transport water and supports the plant using lignin.

  • Palisade mesophyll cell: Rich in chloroplasts for photosynthesis.

Magnification

• Definition: How many times bigger the image is compared to the actual specimen size.

• Formula:

$Magnification = \frac{\text{size of image}}{\text{size of real object}}$

Classification and Kingdoms

• Binomial System: Scientific names consist of Genus and Species (e.g., $Xanthias \, lamarckii$).

• Species: Organisms that reproduce to produce fertile offspring.

• 5 Kingdoms:

  • Fungi: Multicellular, complex, saprophytic.

  • Plant: Multicellular, complex, autotrophic.

  • Protoctist: Mostly unicellular, complex.

  • Animal: Multicellular, complex, heterotrophic.

  • Prokaryote: Unicellular, simple, no nucleus.

• Vertebrates: Mammals (fur/milk), Birds (feathers), Fish (scales/gills), Reptiles (scaly skin), Amphibians (slimy skin).

• Arthropods: Arachnids (8 legs), Crustaceans (10 legs), Insects (6 legs), Myriapods (many legs).

• Plant Kingdom: Mosses & Liverworts, Ferns (reproduce by spores), Gymnosperms (non-flowering/conifers), Angiosperms (flowering; Monocots vs. Dicots).

• Viruses: Non-living; require a host; genetic material wrapped in a protein coat.

Diffusion, Osmosis, and Transport

• Diffusion: Movement of molecules (except water) from high to low concentration. Increasing temperature, concentration gradient, and surface area speeds it up.

• Osmosis: Movement of water molecules only through a semi-permeable membrane.

  • Hypotonic: Dilute solution (high water potential).

  • Hypertonic: Concentrated solution (low water potential).

  • Isotonic: Equal concentration.

• Effects on Cells:

  • Plants: Become turgid in hypotonic solutions; flaccid/plasmolysed in hypertonic solutions.

  • Animals: May burst (lysis) in hypotonic solutions; shrink in hypertonic solutions.

• Active Transport: Movement of ions/solutes against a concentration gradient (low to high) using energy.

Biological Molecules and Enzymes

• Molecules:

  • Carbohydrates & Fats: Carbon, Hydrogen, Oxygen ($CHO$).

  • Proteins: Carbon, Hydrogen, Oxygen, Nitrogen, Sulphur ($CHONS$).

  • Nucleic Acids: Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus.

• Food Tests:

  • Iodine Test: Starch (Positive: blue-black; Negative: brown).

  • Biuret Test: Protein (Positive: purple; Negative: blue).

  • Ethanol Emulsion: Lipids (Positive: cloudy emulsion).

  • Benedict Test: Reducing sugar + $65^{\circ}C$ water bath (Positive: orange/brick red).

• Enzymes: Biological catalysts with specific active sites.

  • Temperature: Rate increases until optimum, then protein denatures.

  • pH: Different enzymes have different optimums (e.g., Pepsin at $pH \, 2$; Amylase at $pH \, 7.5$).

Photosynthesis and Plant Nutrition

• Equation:

$6CO_2 + 6H_2O \rightarrow C_6H_{12}O_6 + 6O_2$

• Limiting Factors: Light intensity, $CO_2$ concentration, and temperature.

• Minerals:

  • Magnesium: Required for chlorophyll; deficiency causes chlorosis (yellowing).

  • Nitrate: Required for amino acids; deficiency causes stunted growth.

Plant Transport and Gas Exchange

• Transpiration: Loss of water vapor via stomata. Driven by transpiration pull (cohesion and adhesion).

• Translocation: Movement of sucrose and amino acids in phloem from source (leaf) to sink (roots/fruits).

• Leaf Anatomy:

  • Palisade mesophyll: Main site of photosynthesis.

  • Spongy mesophyll: Air spaces for gas exchange.

  • Guard cells: Control stomata opening.

Human Nutrition and Digestion

• Dietary Needs: Carbohydrates (energy), Proteins (growth), Vitamin C (skin/gums), Vitamin D/Calcium (bones), Iron (haemoglobin), Fiber (constipation prevention).

• Teeth: Incisors (biting), Canines (tearing), Premolars/Molars (grinding). Structure: Enamel, Dentin, Pulp.

• Digestive Organs:

  • Mouth: Amylase digests starch to maltose ($pH \, 7.5$).

  • Stomach: Pepsin digests protein ($pH \, 2$); $HCl$ kills bacteria.

  • Duodenum: Pancreatic juice (amylase, trypsin, lipase); Bile (emulsifies fats).

  • Ileum: Villi absorb nutrients; Maltase digests maltose to glucose ($pH \, 8$).

  • Colon: Water absorption.

Respiration and Gas Exchange

• Aerobic Respiration:

$C_6H_{12}O_6 + 6O_2 \rightarrow 6H_2O + 6CO_2 + 36ATP$

• Anaerobic Respiration:

  • Humans: $Glucose \rightarrow Lactic \, acid + energy$

  • Yeast: $Glucose \rightarrow Ethanol + Carbon \, dioxide + energy$

• Breathing Mechanism: Inhalation involves external intercostal muscle and diaphragm contraction, increasing volume and decreasing pressure.

• Alveoli: Site of gas exchange; features thin walls, large surface area, and moist surfaces.

Circulation and Blood

• Heart:

  • Right Side: Vena cava, Right Atrium, Right Ventricle, Pulmonary Artery (deoxygenated blood).

  • Left Side: Pulmonary vein, Left Atrium, Left Ventricle, Aorta (oxygenated blood).

• Blood Vessels: Arteries (high pressure, thick walls), Veins (low pressure, valves, wide lumen), Capillaries (one cell thick).

• Blood Components: Erythrocytes (oxygen), Phagocytes (engulfing), Lymphocytes (antibodies), Thrombocytes (clotting via fibrinogen to fibrin conversion), Plasma (transport).

Disease, Immunity, and Drugs

• Malaria: Vector (Female $Anopheles$ mosquito); Pathogen ($Plasmodium$ parasite).

• Cholera: Pathogen ($Vibrio \, cholerae$). Produces toxins causing chloride ion release ($Cl^-$) and water loss via osmosis leading to diarrhea.

• HIV: Transmitted via body fluids; weakens immune system by reducing lymphocytes.

• Immunity:

  • Active: Body produces antibodies (infection or vaccine).

  • Passive: Antibodies transferred from another (placenta/breast milk).

• Drug Effects:

  • Smoking: Tar (cancer), Nicotine (addiction/vasoconstriction), Carbon Monoxide (reduces oxygen transport).

  • Alcohol: Liver damage (cirrhosis), increased reaction time, reduced self-control.

• Antibiotics: Kill bacteria; misuse leads to resistant "Superbugs" like $MRSA$.

Excretion and Homeostasis

• Kidney & Nephron:

  • Ultrafiltration: In the Glomerulus; small molecules enter Bowman’s capsule as filtrate.

  • Selective Reabsorption: Glucose, salts, and water reabsorbed in the Loop of Henle.

• Liver: Performs deamination (excess amino acids converted to urea and carbon skeleton).

• Negative Feedback: Homeostatic mechanism to return internal conditions (temperature, glucose) to set points.

• Skin: Controls temperature via Vasodilation (hot) and Vasoconstriction (cold).

• Blood Glucose: Insulin (lowers glucose by storing it as glycogen); Glucagon (raises glucose by breaking down glycogen).

Coordination and Tropisms

• Nervous System: CNS (Brain, Spinal cord) and PNS (Nerves).

• Reflex Arc: $Stimulus \rightarrow Receptor \rightarrow Sensory \, neurone \rightarrow Relay \, neurone \rightarrow Motor \, neurone \rightarrow Effector$.

• Synapse: Junction between neurones where neurotransmitters diffuse across the gap.

• The Eye:

  • Accommodation: Ciliary muscles and suspensory ligaments change lens shape for near/far focus.

  • Pupil Reflex: Circular and radial muscles adjust pupil size to light intensity.

• Plant Tropisms: Controlled by Auxin.

  • Phototropism: Shoots grow towards light (positive).

  • Gravitropism (Geotropism): Roots grow towards gravity (positive); shoots grow away (negative).

Questions & Discussion

Magnification Practice

• Question: A plant cell is magnified $X1000$. If the size of the image is measured at $50\,mm$, what is the actual size of the plant cell?

• Response: Using the formula $Actual \, size = \frac{Image \, size}{Magnification}$, the result is $50\,mm / 1000 = 0.05\,mm$.

Food Test Identification

• Question: Can you identify from the food tests above which are the positive and negative results?

• Response:

  • Iodine: Blue-black (+) vs brown (-).

  • Biuret: Purple (+) vs blue (-).

  • Ethanol: Cloudy emulsion (+) vs no emulsion (-).

  • Benedict: Orange to red brick color (+) vs blue (-).

Cell Structure and Specialized Cells

• Animal Cell Structures:

  • Nucleus: Contains genetic material (DNA); regulates gene expression.

  • Ribosome: Free ribosomes synthesize proteins for internal use; bound ribosomes for export.

  • Mitochondria: Also involved in apoptosis (programmed cell death); contain their own DNA.

  • Cytoplasm: Includes cytosol and organelles; site for anaerobic respiration.

  • Cell membrane: Composed of a phospholipid bilayer, with embedded proteins and cholesterol for fluidity.

• Plant Cell Structures:

  • Cell wall: Composed mainly of cellulose; provides structural support and protection against pathogens.

  • Sap vacuole: Also involved in storing waste products and maintaining turgor pressure for structural support.

  • Chloroplast: Contains photosystems for light absorption; involved in synthesis of glucose and storage of starch.

• Bacterial Cell:

  • Plasmid: Can carry genes for antibiotic resistance or other traits; can be exchanged between bacteria.

  • Circular DNA: Not associated with histones, allowing for faster reproduction.

• Specialized Animal Cells:

  • Ciliated cell: Found in the respiratory tract; helps trap and move debris.

  • Sperm cell: Contains mitochondria for energy; acrosome contains enzymes to penetrate the egg.

  • Egg cell: Contains yolk; provides nutrients for the developing embryo.

  • Nerve cell/neurone: Myelin sheath increases impulse speed; dendrites receive signals.

  • Red blood cell: Lacks a nucleus for more space for hemoglobin; biconcave shape increases surface area for oxygen absorption.

• Specialized Plant Cells:

  • Root hair cell: Large surface area enhances water absorption; contains mineral transport proteins.

  • Xylem vessel: Lignin strengthens walls; enables water transport under negative pressure.

  • Palisade mesophyll cell: Maximizes light absorption; contains chlorophyll to increase efficiency of photosynthesis.