chapter 1 Flashcards
what is the cell theory?
- all living things are made of cells
- cells are the smallest unit of life
- cells can only come from preexisting cells
what are all the necessary functions of survival?
metabolism, response, homeostasis, nutrition, excretion, reproduction, growth
example of a unicellular organism
paramecium
equation to calculate magnification?
magnification = image size / actual size
what does the volume of a cell determine?
the level of metabolic activity that takes place
what does the surface area of a cell determine?
the rate of exchange of materials
what are the advantages of multicellular organisms?
- cells can differentiate so that organisms can grow in complexity
why does differentiation increase complexity?
cells can interact with each other
- eg nerve cells and muscle cells react to stimulate movement
how does specialist tissue form?
cell differentiation in multicellular
organisms.
how do cells differentiate?
different genes are expressed in the cells genome
why are stem cells useful for therapeutic treatment?
because they are pluripotent and can differentiate into several types of cell rapidly
ethical issues with stem cell treatment?
destruction of a potential child is imoral. if we have a treatment why should it be refused
therapeutic uses of stem cells ?
treating leukaemia patients after chemotherapy
what is the structure of prokaryotic cells
simple structure without compartmentalization
what is the cell wall
surrounds the cell and protects is from bursting
what is the plasma membrane
controls the movement of materials into and out of the cell
what is a ribosome
where proteins are synthesised
what is a flagellum
enables cells to move
what is the structure of eukaryotic cells
compartmentalised (contains organelles)
what is a rough ER
an ER with ribosomes attached
what is a smooth ER
an ER with no ribosomes attached
what is golgi apparatus
stacks of flattened membranes responsible for processing proteins made in the rER
what are lysosomes
spherical organelle responsible for breaking down components of cells
what is the cell membrane made of?
phospholipids, cholesterol, proteins
what is the role of cholesterol in the cell membrane
makes membrane less ‘fluid’, more rigid, and less permeable to water-soluble molecules
what are integral proteins?
proteins embedded in the bilayer
what are peripheral proteins?
attached to the surface (mainly glycoproteins)
who came up with the fluid mosaic model?
singer and nicolson
what is passive transport?
the movement of substances down a concentration gradient without the need for energy
what is diffusion?
a form of passive transport
what is osmosis ?
passive transport where water moves across a partially permeable membrane from high to low concentration
what is active transport?
the movement of substances against the concentration the involves energy in the form of ATP
what is the role of channel proteins?
channel proteins are required so that water-soluble materials can pass through
what is facilitated diffusion?
diffusion across a membrane through specific channel proteins in the membrane without the use of ATP
what is water potential?
the tendency of water molecules to move from an area of high concentration to an area of low concentration
what is endocytosis?
substances are takes into the cell by indention of the cell membrane requiring ATP
what is exocytosis?
substances expelled from the cell requiring ATP
how are cells formed?
cells can only be formed by division of preexisting cells
what is the endosymbiotic theory?
how eukaryotic cells could have developed from simple or prokaryotic cells
what is the evidence for the endosymbiotic theory?
mitochondria and chloroplast contain ribosomes identical to the ones in bacteria, have their own envelope surrounding them and can replicate themselves by binary fission
what is a gene?
a length of dna at a specific location on a chromosome that controls a specific heritable characteristic
what are the 3 stages of the cell cycle?
interphase, mitosis, cytokinesis
what happens in G1?
cell grows, DNA is transcribed, protein is sythesised
what happens in the S phase?
DNA is replicated
what happens in G2?
cell prepares for devision
what happens in mitosis?
cell nucleus divides
what happens in cytokinesis?
cytoplasm divides
what happens in interphase?
the DNA in the nucleus is replicated, proteins synthesised, no. of mitochondria increase
what happens in prophase?
chromosomes become visible and have been drawn into long threads. supercoiling occurs
what happens in metaphase?
nuclear envelope is broken down, chromatids align themselves in the middle
what happens in anaphase?
centromeres split and sister chromatids are pulled apart, each chromatid is now a chromosome
what happens in telophase?
spindle fibres break down and a nuclear envelope forms around each set of chromosomes
what is supercoiling?
the condensation of chromosomes
what are cyclins?
cyclins are compounds that are involved in the control of the cell cycle
what are mutagens?
an agent that causes mutation
what is metastasis?
when primary tumours migrate to other tissue and form new secondary tumours
what are oncogenes?
a cancer-initiating gene
why do oncogenes become active?
mutation in another gene, direct exposure to mutagen and environmental factor eg viral infection
