bio 1 general (p) Flashcards
Diffusion is
the passive movement of substances down a concentration gradient.
Osmosis is
a special case of diffusion in which water moves from a solution of higher water potential to a solution of lower water potential through a partially permeable membrane.
What does TEM stand for?
Transmission Electron Microscope
What organelles make up an epithelial cell found in the small intestine? These organelles can not have been seen using an optical (light) microscope. Explain why.
Nucleus (nucleolus, double membrane, chromatin), mitochondria, ribosomes, smooth ER, rough ER, lysosomes, microvilli and golgi Optical microscope not useful because1. Has low resolution/not high enough resolution;2. (Because) wavelength of light not short enough/too long;
Describe the nucleus
Made up of the nuclear pore, nuclear envelope, chromatin and the nucleolus. Codes the proteins in the DNA to allow it to carry out its tasks
Nuclear pore
Gaps in the nuclear envelope to allow larger molecules out of the nucleus such as mRNA
Chromatin
DNA not sorted into chromosomes
Nucleolus
Helps in producing ribosomes
Mitochondrion
Job is to produce ATP, this releases energy. Provides energy for the cell, through aerobic respiration. Aerobic respiration occurs within the matrix
Why do some cells have more mitochondrion?
They have a more active metabolism, need more energy
Rough ER
Rough endoplasmic reticulum has ribosomes attached. Its job is to produce proteins/glycoproteins and to transport proteins
Smooth ER
Smooth endoplasmic reticulum, found and attached to the nuclear envelope. The job is to produce lipids, steroids and carbohydrates. Also to store carbs
Golgi Apparatus
These also produce glycoproteins and secretory enzymes as well as lysosomes. Modifies and stores lipids. Vesicles transport proteins or substances made by the golgi to inside or outside of the cell
Lysosomes
Structures which contain enzymes produced by the golgi, these destroy weak or old cells or organelles.
Ribosomes
Very small, site of protein synthesis
Types of microscope
Light, transmission or scanning electron microscope
Light microscopes
1500x magnification, easy to use. Used in schools. Light rays are used to see it. Problem - cannot see things inside of the cells as the wavelength is relatively big
Electron microscope
Much smaller wavelengths. Uses electrons. SEM- electrons are reflected off the surface for a 3D image. 100,000x magnification. TEM - Electrons pass through the object, images are 2D, 500,000x magnification. The training and preparation is a excessive
mm
x10^3
um
x10^6
nm
x10^9
image size =
image size =actual size x magnification
Magnification
MagnificationHow many times bigger an image is than the object
Resolution
The smallest distance between two objects that means they can be seen as separate
Eukaryotic cells
animal and plant cells
Ultracentrifugation
Cell fractionation to break and rupture cells, done using a blender with the cells in a buffered, ice-cold and isotonic solution. It is then spun in the centrifuge causing the heaviest organelles to form a sediment and the rest form the supernatant
What is the cell membrane made of?
Made of phospholipids with proteins floating in between.
What is the membrane referred to as, why?
Fluid mosaic model because the phospholipids move around and are fluid.
How is the membrane arranged?
The phospholipids are arranged in two layers. The phosphate heads are polar molecules and so are water-soluble whilst the lipid tails are non-polar so are not water - soluble. This means that the phospholipids are arranged with the heads near cytoplasm
What do the proteins in the membrane do?
Proteins in the membrane line pores in the lipid layer. The polar groups of the protein molecules mean that substances that would not be able to penetrate the lipid layer (lipid insoluble) can still move through the membrane
What do the polysaccharide chains in the membrane do?
membraneThese are attached to the proteins and are called glycoproteins and help with the recognition and interaction with other cells
What about cholesterol in the membrane
Maintains fluidity and increases stability
Functions of the membrane (6)
- selectively permeable barrier2. structural, keeping the cell contents together,3. allows communication with other cells, 4. allows recognition of external substances, 5. allows mobility in some organisms 6. the site of various chemical reactions
Cholera bacteria are prokaryotic cells. Give three structures found in prokaryotic cells but not in eukaryotic cells.
Capsule / glycocalyx / slime layer;Circular / ring of / non-linear DNA / DNA without histones; Plasmid;Flagellum;Pilus;Small / less dense / 70s ribosomes;
Many different substances enter and leave a cell by crossing its cell surface membrane. Describe how substances can cross a cell surface membrane.
1 (Simple / facilitated) diffusion from high to low concentration / down concentration gradient;2 Small / non-polar / lipid-soluble molecules pass via phospholipids / bilayer;ORLarge / polar / water-soluble molecules go through proteins;3 Water moves by osmosis / from high water potential to low water potential / from less to more negative water potential;4 Active transport is movement from low to high concentration / against concentration gradient;5 Active transport / facilitated diffusion involves proteins / carriers;6 Active transport requires energy / ATP;7 Ref. to Na+ / glucose co-transport;
Coeliac disease is a disease of the human digestive system. In coeliac disease, the microvilli are damaged.Although people with coeliac disease can digest proteins they have low concentrations of amino acids in their blood.Explain why they have low concentrations of amino acids in their blood.
Reduced surface area; (So) less absorption;(Membrane-bound) enzymes less effective; (So) proteins / polypeptides not digested;Cell membranes damaged;(So) Fewer / less effective carrier / channel proteins;Carrier / channel proteins damaged; (So) less absorption;
Some students were advised in an experiment that they could improve the reliability of their results by taking additional readings. Explain how
Anomalies to be identified or the effect of anomalies to be reducedA mean to be calculated;
Some cells lining the bronchi of the lungs secrete large amounts of mucus. Mucus contains protein.Name one organelle that you would expect to find in large numbers in a mucus-secreting cell and describe its role in the production of mucus
Organelle named; Function in protein production/secretion;eg1. Golgi (apparatus);2. Package/process proteins;OR3. Rough endoplasmic reticulum/ribosomes;4. Make polypeptide/protein/forming peptide bonds;OR5. Mitochondria;6. Release of energy/make ATP;OR7. Vesicles;8. Secretion/transport of protein
An enzyme catalyses only one reaction. Explain why
- (Enzyme has) active site2. Only substrate fits (the active site)
