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IB SL Biology - Cells
Terms in this set (69)
These organelles are the sites of translation of DNA for the synthesis of proteins. They function as a workbench for protein synthesis, they receive and translate genetic instructions for the formation of specific proteins.
A cell characterized by the presence of a nucleus and other membrane-bound organelles. Eukaryotes can be unicellular (protists) or multicellular (fungi, plants and animals).
The assembly of chains of amino acids into functional protein molecules.
Region containing closed-loop DNA.
The smallest unit of life.
Cells that came first in terms of evolution.
Prokaryotic Cell parts
Cell parts that are NOT membrane-bound, hence, they are NOT organelles.
Means 'two splitting'. Prokaryotic's reproduce like this. The stages are as follows:
Bacterium starts a DNA loop
Cell grows and DNA loop replicates semiconservatively
DNA loops pulled to opposite sides of the diving cell
The new cells are called 'daughter' cells. They are clones as they contain identical DNA
Smaller unicellular organisms were engulfed and became parts of larger organisms, eventually becoming organelles in the cell.
The outer limit of the cell controls entry and exit of nutrients and waste.
Membrane-bound nucleus contains all genetic information in chromosomes. The nucleolus is a densely-packed area of DNA.
Rough Endoplasmic Reticulum
Ribosomes on rough ER produce proteins to be exported from the cell.
Contains many enzymes and solutes needed for metabolic reactions within the cell, as well as dissolving mineral ions, nutrients and waste.
Site for respiration: converts sugars into ATP (a more useful store of energy).
Free Ribosomes (Eukaryotic)
Produce proteins to be used by this cell.
Waste disposal (contains hydrolytic enzymes)
Breaks down 'dead' cellular machinery
Golgi apparatus (Eukaryotic)
Modifies and 'packages' proteins produced in the RER to be exported by the cell via exocytosis.
Support and structure. In PLANT cells, they are composed of CELLULOSE. In FUNGI, they are composed of CHITIN. In PROKARYOTES, they are composed of MURIEN
Contain chlorophyll for photosynthesis.
Storage of water or sugars.
A lipid made of a phosphate group and two fatty acids
The Fatty Acid is Hydrophobic (it doesn't mix with water)
Fluid Mosaic Model
A bilipid layer with protein + Cholesterol molecules between the phospholipids and polysaccharides attached to the proteins or lipids and constantly moving.
Branching carbohydrate portion of a protein which acts as a recognition site for chemicals.
Acts as a recognition site e.g. for cholera toxins.
They create pores through which water and water soluble chemicals can pass. They also act as carriers in Active Transport. (very important in Cell Recognition)
The movement of a substance from a high concentration to a low concentration down a concentration gradient
The movement of water from a high concentration to a low concentration down a concentration gradient
Specific proteins in the cell membrane help to SPEED UP DIFFUSION by passing substances across the membrane. Proteins may form ion channels (pores) which can open and close and move selected ions, e.g. sodium or potassium
Solute and water concentrations equal on both sides of membrane
Concentration of solute lower than on other side
Concentration of solute higher than on other side
This process allows materials to move against a concentration gradient. It relies on carrier proteins in the cell membrane. Transport molecules attach to the carrier protein which undergoes a conformational change due to the energy from the hydrolysis of ATP. (Adeonine Triphosphate).
Macromolecules transported into or out of the cell inside vesicles.
Vesicles fuse with plasma membrane and secrete contents (hormone secretion)
Cells engulf substances into pouch which becomes a vesicle
Chromatin condenses = supercoiling. Nuclei breaks down and centrosomes move apart
Dissapearance of nuclear membrane. Spindle invades the nuclear region. Spindle fibres form and attach to centromere of sister chromatids, they align in thimble of cell
The captured chromosomes are pulled to the equatorial plane
The Centrometres divide. Two processes: spindle fibres shorten and poles move apart. This moves the chromosomes across to their separate destinations
Spindle breaks down. Chromosomes elongate as chromatid uncoils. Nuclear envelope forms and so does the nuclei
Cell division that produces reproductive cells in sexually reproducing organisms
Involved in synthesis and modification of materials before they leave the cell. THE GOLGI APPARATUS IS FULL OF ENZYMES
Eukaryotic Cells Size
Approx 100 micro meteres
Smooth Endoplasmic Reticulum
Stem cells that had the ability to differentiate into all types of cells
Stem cells with the potential to differentiate into most any type of cell
Tiny circles of DNA, separate from the main circle of DNA. They usually carry non-essential genes e.g. Antibiotic material
A whip-like tail which produces a rotational movement, which allows bacteria to be mobile
A layer of slime around the bacteria. It protects the bacteria from drying out and being digested by enzymes
When bacteria reproduces
A cell plate is formed along the middle of the cell, allowing the cell wall to cleave the cell into two
Exam Question: Explain how Mitosis ensures that daughter nuclei are genetically identical.
Exact copies of DNA are made during interphase S Phase
DNA Replication is included to make sure that no mistakes have taken place
DNA is supercoiled
In METAPHASE, all sister chromatids are lined up at the equator
When the spindle microtubules attach to the centrometre, they are in the correct position - one copy facing each pole of the cell
In anaphase, these chromatids are pulled apart - exactly the right no. are pulled in one direction
At telophase, the chromosomes have reached the poles
There is clear space between the newly reformed nuclei to allow the cell to divide by cytokinesis, ensuring no chromosomes are caught on the wrong side.
Substance responsible for causing mutations and most notably cancer.
cell mass from uncontrolled cell division
tumour recruits blood vessels and grows larger
Are folds giving surface area for metabolic process in the cell membrane and allow some compartmentalization.
An infolding of the inner membrane of a mitochondrion that houses the electron transport chain and the enzyme catalyzing the synthesis of ATP.
Chitin and Muriel
Two types of cell wall components. One is used in Fungi and the other is used in Bacteria.
Population growth by Binary Fission would be 'Exponential' - what does this mean?
As time increases, the rate of growth of population grows (until there are no more resources for extra growth)
Controlled entry/exit of substances
of a cell or organism having two sets of chromosomes or twice the haploid number
(genetics) an organism or cell having only one complete set of chromosomes
Growth and replication of organelles
Assembly of spindle begins
Synthesis of DNA