Topic 2A Flashcards
Eukaryotic cells are ..
Are complex and include All animal and plant cells as well as fungi and algae
Prokaryotic cells are…
Single called organisms
What extra organelle do plant cells have
Cellulose cell wall with plasmodesmata
Vacuole
Chloroplasts
Difference between fungal and plant cell
Fungal cell walls made of chitin not cellulose
Fungal calls don’t have chloroplasts
Cell surface membrane function
Regulates movement of substance in and out of cell. Has receptor molecules to respond to chemicals like hormones
Nucleus function
Controls cell activity
Pores allow substances to move between nucleus and cytoplasm
Nucleulous makes ribosomes
Mitochondrion function
Site of aerobic respiration where atp produced
Chloroplasts function
Site of photosynthesis some happens in grana and other in stroma
Lamellae
Thin flat pieces of thylakoid membrane
Stroma
Thick fluid found in chloroplasts
Golgi apparatus function
Processes and packages new lipids and proteins and makes lysosomes
Golgi Vesicles function
Stores lipids and proteins made by Golgi and transports out the cell via cell surface membrane
Lysosomes function
Contains digestive enzymes called lysozymes. Kept separate from cytoplasm by surrounding membrane and can be used to digest invading cells or break down worn out components of cell
Ribosome function
Site where proteins are made
Rough endoplasmic reticulum function
Folds and processes proteins that have been made at the ribosomes
Smooth endoplasmic reticulum
Synthesises and processes lipids
Cell wall function
Supports cell and prevents it changing shape
Cell vacuole function
Helps to maintain pressure inside the cell and keep it rigid
Stops wilting
Involved in isolation of unwanted chemicals inside the cell
Capsule
Made of secreted slime, helps protect bacteria from attack cells from immune system
Plasmids
Small loops of DNA that contain genes for things like antibiotic resistance
Flagellum
A long hair like structure that rotated to make the prokaryotic cell move
4key points about viruses
Just nucleic acids surrounded by protein, not alive
Smaller than bacteria
Have no plasma membrane, no cytoplasm and no ribosomes
Reproduce inside host cells
Virus structure
Contain a core of genetic material either DNA or RNA
Protein coat around core is capsid
Attachment proteins stick out from edge of capsid so can cling on host cell
Binary fission
Circular DNA and plasmids replicate
Cell gets bigger and DNA loops move to opposite poles of cell
Cytoplasm begins to divide and cell walls begin to form
Cytoplasm divides and two daughter cells produced with one copy of circular DNA each
Light microscopes
Source : Light radiation
Magnification: upto 1500x
Resolution : 0.2 micrometers
Resulting image: black and white 2D
Sample preparation for light microscope
Sample is washed, add a simple chemical and put a cover slip over it
Scanning electron microscopes
Source: Scan beam of electron across specimen knocking off electrons from specimen and gathering in cathode tube to form image
Resolution: 20nm, lower than TEM
Magnification: x1,500,000
Resulting image: 3D image
SEM sample preparation
Coat specimen with thin layer of gold
Must be in a vacuum
Transmitting electron microscope
Source: Electromagnets focus beams of electrons which is then transmitted through specimen
Resolution: 0.1 nm, high
Resulting image: 2D Black white
TEM sample preparation
Must be in a vacuum
Slice and stain
Homogenisation
Done by vibrating cells or grinding in blender. Breaks up the plasma membrane and releases organelle into solution
Solutions must be ice cold to reduce enzyme activity that break down organelle
Must be isotonic, and use buffer solution
Filtration
Homogenised cell solution filtered through gauze to separate large debris or tissue
Ultracentrifugation
Cell fragments poured into tube which is put in centrifuge and spun at low speed. Heaviest organelle like nuclei form pelt
Supernatant drained off and spun at higher speed, repeated with higher speeds until all organelles are separated
Interphase
Cell prepares to divide
DNA unravels and replicated to double genetic content
Prophase
Chromosomes condense getting shorter and fatter
Bundles of proteins called centrioles move to opposite ends of the cell forming network of protein fibres called spindles
Nuclear envelope breaks down and chromosomes lie free in cytoplasm
Metaphase
Chromosomes line up along the equator and become attached to spindle by there centromere
Anaphase
Centromeres divide departing each pair of sister chromatids. Spindles contract pulling chromatids to opposite poles of the spindle, centromere first
Telaphase
Chromatids reach opposite poles on the spindle. Uncoil and become long and thing again (chromosomes)
Nuclear envelope forms around each group of chromosomes
Cytokinesis
Cytoplasm divides and there are now two daughter cells that are genetically identical to original
Cancer treatment: G1 (cell growth and protein production)
Some chemical drugs prevent synthesis of enzymes needed for DNA replication.
If these aren’t produced cell unable to enter synthesis phase forcing to kill itself
Cancer treatment: S Phase (DNA replication)
Radiation and some drugs damage DNA, if damaged DNA detected, it will kill itself
Not enough DNA for two daughter nuclei
Ribosomes found in prokaryotic cells
70S
