Exam Flashcards
Cell theory
All living things are composed of one or more cells.
All cells arise from pre-existing cells through cell division.
The cells is the fundamental unit of structure and function in all livings organisms.
The characteristics of prokaryotes.
Cell wall: Maintains the characteristic shape of the cell by providing rigidity and structural support.
Capsule: An external cell-covering that provides protection from host cells. The capsule is sticky allowing bacteria to adhere to the surfaces.
Pili: Thin protein fibres that serve to attach to bacteria to a surface, other bacteria and target cells.
Flagella: Motile bacteria contain fibrous projections that propel the cell through its environment.
DNA: Prokaryotes posses a single, continuous, circular molecule of DNA located in a region of the cytoplasm called the nucloid.
Plasmids: Circular DNA molecules that are not part of the main chromosome. Plasmids contain a small number of genes for metabolisms, virulence and residence to antibiotics.
Features of eukaryotic cell
Nucelus: The location of chromosomes. DNA replication and transcription occur in the nucleus.
Nucleolus: Contain genes for the synthesis of ribosomal RNA (rRNA). rRNA is required for ribosome synthesis.
Mitochondrion: Involves the process of cellular respiration that is used to synthesise ATP.
Chloroplast: Chloroplasts are light-absorbing organelles that carry out the process of photosynthesis.
Vacuole/ Vesicle: Membrane-bound organelles that store store water. Vesicles are membrane-bound packages containing material be secreted from the cell.
Golgi body: Golgi body modifies proteins before packaging the modified products in vesicles. The vesicles are transported to the membrane or the cytoplasm cell.
ER: An interconnected membrane system of hollow tubes and that is involves in the synthesis of proteins and phospholipids. The ER has two seperate components the rough and smooth ER. The rough ER has ribosomes on its surface and is the site of protein synthesis. The smooth ER has no ribosomes.
Lysosome: Vesicles containing enzymes that digest old organelles, storage molecules and whole cells.
Cytoskeleton: A network of long protein fibres that provide mechanical support that enables the cell to carry out essential functions including movement and cell division.
Type of prokaryotic shapes
Sphere, rod and spiral.
What is an Autotroph?
Organism that produces its own food and energy sources using non-living materials in the environment.
What is a Heterotroph?
Organism that obtains food and energy by consuming materials derived from other living things (herbivores, omnivores and carnivores).
Photosynthesis reaction
chlorophyl
6CO2 + 6H2O ——————-> C6H12O6 + 6O2
sunlight
Aerobic respiration reaction
C6H12O6 + 6O2 ——————-> 6CO2 + 6H2O + energy
Difference between anabolic and catabolic
Anabolic is synthesis of a larger molecule to a smaller molecule and catabolic is the breaking down of a larger molecule to a smaller molecule.
ATP reactions
energy
ADP + Pi ——————-> ATP
H2O ATP -------------------> ADP + Pi
What can ATP be used for
Movement: ATP powers the movement of flagella in sperm and bacteria, the protein fibres (actin and myosin) that control muscle movement, and the cilia that move mucus in respiratory system.
Growth and reproduction: ATP is used to move chromosomes around the cell in mitosis and meiosis. ATP is used in attaching an amino acid to a tRNA, as well as joining amino acids to form a polypeptide in protein synthesis.
Respiration: ATP is used in some chemical reactions that occur in aerobic respiration such as the conversion of glucose to glucose-6-phosphate.
Nutrition: ATP is used in the active transport of waste materials against the concentration gradient in animals, plants, and microorganisms.
Response to stimuli: ATP is used in the synthesis of peptide hormones as well as the transmission of ions and neurotransmitters in the synapses of the animal nervous system.
ATP yields for Aerobic respiration, alcohol fermentation and lactic acid fermentation.
Aerobic respiration: 36-38
Alcohol fermentation: 2
Lactic acid fermentation: 2
Raw materials (input) of plants and waste materials (output) for autotrophs
Raw (input)
Photosynthesis: carbon dioxide.
Aerobic respiration: Glucose and oxygen.
ATP/ nucleotide/ phospholipid synthesis: phosphate ions
Waste (output)
Photosynthesis: Excess oxygen.
Aerobic respiration: Carbon dioxide and water.
Raw materials (input) of plants and waste materials (output) for heterotrophs
Raw (input)
Aerobic resp: inorganic ions, vitamins, glucose and oxygen
Protein synthesis: Amino acids.
ATP/ nucleotide/ phospholipid synthesis: phosphate ions, vitamins and fatty acids.
Waste (output) Aerobic respiration carbon dioxide and water. Anaerobic respiration: Lactic acid. Protein synthesis: Urea. Perspiration: Sodium and chloride ions.
Protein functions in cell membrane
Transport: Channel proteins and carrier proteins transport hydrophilic materials across the membrane.
Receptors: Some proteins recognise and bond to target molecules (such as hormones) causing changes to occur inside cell.
Enzymes: Enzymes imbedded in the membrane catalyse substrate specific reactions at the boundary or within cell membrane.
Cell recognition: Some proteins (namely glycoproteins) serve as markers that are recognised by membrane proteins on the surface of other cells. Identification protects host cells from attack by the immune system.
Osmotic extracellular solutions
Isotonic - solute concentration outside the cell is equal to the to solute concentration inside the cell.
Hypotonic - Solute concentration outside the cell is lower than the solute concentration inside the cell.
Hypertonic: Solute concentration outside the cell is higher than the solute concentration inside the cell.
Physical/ chemical properties of transportation
Small hydrophobic - Diffusion
Large hydrophobic - Bulk transport
Small hydrophilic - Channel proteins and carrier proteins
Large hydrophilic - Bulk transport
Ions - Channel proteins.
Mitochondria structures and roles
Outer membrane: Lipid bilayer membrane containing carrier and channel proteins such as well as enzymes involved in catalysing chemical reactions
Inner membrane: Lipid bilayer membrane containing enzymes that carry out the final stages of aerobic respiration, including ATP synthesis.
Cristae: Extensions of the inner mitochondrial membrane. Cristae increase the surface area to volume ratio of the inner mitochondrial membrane which increases the rate of ATP synthesis in eukaryotic cells.
Matrix: The space enclosed by the inner mitochondrial membrane. The matrix contains mitochondrial DNA, ribosomes and enzymes that carry out important biochemical reactions.
Chloroplast structures and roles
Inner and outer membrane: Regulate transport of materials between the storm and the cytoplasm of a plant cell. The inner membrane contains enzymes that carry out the synthesis of some pigments and lipids.
Thylakoid: Membrane bound sacs containing light-absorbing pigments and enzymes that are involved in the process of photosynthesis.
Granum: A granum (plural; grana) is a stack of thylakoids. Grana increase the surface area to volume ratio of light-absorbing pigments which increases the rate of photosynthesis.
Stroma: A gel-like fluid that contains enzymes which carry out chemical reactions in the process of photosynthesis.
Stromal lamellae: Extensions of the thylakoid membranes that increase the surface area to volume ratio of light-absorbing pigments which increases the rate of photosynthesis.
Biochemical processes in cells can be influenced by environmental factors
Temperature: The rate of enzymes-catalysed reactions increase until the optimum temperature is reached. The reaction decreases at higher temperatures s the enzymes become denatured.
Light intensity: The rate of a light-dependent reaction is affected by the intensity and wavelength of light becoming absorbed.
pH: pH alters the shape (tertiary structure) of an enzyme which decreases the rate of an enzyme-catalysed reaction.
Availability of water: Enzyme-Catalysed reactions occur in the aqueous solution. (water is dependent both the substrate and enzyme concentration).
Chemicals can influence cell metabolism.
Kills pests which reduce crop yields and threaten the health of humans domestic animals and plants. However, some pesticides cause severe illness and can be fatal if they enter the human body.
Fertiliser: Increase crop yields and provides a stable food source to feed the human population. However, fertilisers are synthesised from fossil fuels which are non-renewable resources that emit greenhouse gases upon combustion.
Antibiotics: Kill pathogenic bacteria that cause infectious diseases. Inappropriate and irresponsible use have given rise to antibiotic resistant superbugs that infect humans.
Other pharmaceuticals: Pharmaceuticals improve health, mood and well being by treating illness caused by infectious diseases. Some pharmaceuticals are additive. Drug addictive. Drug addiction can have adverse effects on an individual, as well as their family, friends and community.
Describe binary fission
- DNA is replicated. Both copies of the DNA molecules are attached to the cell membrane.
- The DNA molecules are separated than elongate.
- A cross wall is formed and the membrane invaginate which divides the cytoplasm in two.
- The cross wall is completed.
- Daughter cells seperate from each other.
Cell cycle of prokaryotes.
B - The period between the conclusion of one cell cycle and the initiation of DNA replication in a daughter cell.
C - The period in which DNA synthesis occurs.
D - The period between the completion of DNA synthesis and the completion of cell division.
Cell cycle occurs in three steps for eukaryotes.
Interphase (G1, S and G2 ) Metabolic reactions including DNA and proteins synthesis occur in preparation for cell division.
Mitosis: Prophase, metaphase, anaphase, and telophase. The parent nucleus is broken down and the chromosomes are separated into daughter nuclei.
Cytokinesis: The parent cell divides into two daughter cells that are genetically identical.
Describe what happens on the three stages of interphase
G1 (10 hours) The cell grows and carries out metabolic reactions including protein synthesis. The cell accumulates DNA nucleotides and ATP in preparation for DNA replication in S phase.
S phase (9 hours) Synthesis of DNA. Every chromosome in the nucleus is replicated. The two copies of a chromosome are joined by a centromere. Centrioles divide in preparation for mitosis.
G2 (4 hours) Some organelles are replicated, ATP is replenished, the cytoskeleton is dismantled in preparation for mitosis, and protein synthesis continues.
Describe what happens in the checkpoints for cell cycle
G1 - The chromosome are checked for mutations and other forms of damage at the G1 checkpoint. The availability of DNA nucleotides, DNA polymerase enzymes and ATP is also assessed. The cell is prevented from entering S phase if one or more conditions are unfavourable for DNA replication.
G2 - The genome is checked to ensure that all chromosomes have been replicated and that each chromosome is free from mutations and damage before the cell enters mitosis (M Phase)
M - The sister chromatids are checked to ensure that the centromere is attached to two spindle fibres before the chromatids are irreversibly separated in anaphase.
Describe what proto-oncogenes and tumour suppressing gene do
Proto-oncogenes: Code for proteins that promote cell growth and division (activators of the cell cycle).
Tumour suppressing gene: Code for proteins that inhibit cell growth and division (suppressors of the cell cycle).
Conditions required for cell growth in cell culture
Nutrients: Cells require macronutrients and micronutrients for metabolic reactions involved in growth and development.
Oxygen: Aerobic cells are cultured in the presence of oxygen.
Growth factors: Growth factors and hormones are adde in the concentrations that stimulate growth and development.
Osmotic balance: The amount of water and solutes are controlled to ensure an osmotic balance between cells and the extracellular environment.
pH: Cells are cultured in a medium that has the optimum pH for enzyme activity. pH buffers are added to maintain the optimum pH.
Temperature: Cells are cultured in a medium that has the optimum temperature for enzyme activity.
Antibiotics are added to kill bacteria that would contaminate the culture.
Applications of cell culture.
Research - Scientists culture different cell types to study cell structure and function.
Toxicology - Scientists study the effect of different concentration of new and existing drugs on the structure and function of cells.
Cancer research - Scientists study the properties of cancer cells as well as the effects of ionising radiation and different drugs to improve targeted radiotherapy and chemotherapy techniques.
Research virology - Scientists study the interactions between viruses and cultured cell lines for the development of new drugs and vaccines.
Genetic engineering - scientists modify DNA sequences in cultured cell lines before introducing modified cells to a transgenic organism for growth and development. This technique is used in research as well as the develop products for commercial applications.
Advantages of cell culture
The environmental factors can be controlled to ensure optimal growth rate of cells.
Is used to effectively study interactions between medicines and different cell types.
Is used by medical scientists to effectively diagnose a disease from a tissue sample obtained from a patient.
New antibodies and vaccines can be synthesised and their effects on cells can be studied outside the body.
Cultured cells can be persevered and studied for years following the initial growth phase.
Limations of cell culture
Contamination by microbes and other cell types is possible in laboratory.
Studying the effects of drugs and pathogens on a targeted cell does not identify all effects of the drugs or pathogen in the body of an organism.
Rapid growth rate of cells introduces mutations and genetic variation which is undesirable in a tissue culture.
Studies have revealed differences in protein expression and other metabolic reactions in cultured cell types.
Non-cancerous cell lines have a finite capacity for growth by cell division. The morphology and biochemistry of cells changes with age.
Vegetive propagation steps
1 - A small piece of plant tissue (explant) is removed from the plant through dissection.
2 - The explant is transferred to a growth medium containing growth factors that induce cell division.
3 - Cells in the tissue start to divide forming a shapeless, undifferentiated mass called callus.
4 - The callus is treated with growth hormones at the appropriate concentrations to induce growth of roots and shoots.
5 - Established plants are transferred to soil and grown under optimal conditions. Plants cultured in this way are clones.
