YR11 - Topic Test 1 - Cells, Moving Through Plasma Membrane Flashcards
cells
- they are the basic unit of all living things
- they come from pre-existing cells
- smallest living organisational unit
prokaryotic cells vs eukaryotic cells
prokaryotic cells have no nucleus circular DNA and no membrance bound organelles (bacteria) whereas eukaryotic cells have a nucleus, linear DNA and membrane bound organelles (animals and humans)
nucleus
contains DNA and controls cells activity
rough e.r.
controls what goes in and out of the cell, produces proteins
smooth e.r.
makes cellular products like hormones and lipids.
mitochondria
where aerobic respiration takes place, converts ATP into glucose, this process is known as respiration
ribosomes
where protein synthesis occurs
golgi apparatus
modifying, sorting and packaging of proteins for secretion. It is also involved in the transport of lipids around the cell, and the creation of lysosomes
chloroplast
found in plant cells. Contain chlorophyll that absorbs light for photosynthesis.
large vacuole
found in plant cells. Contain a fluid called cell sap Stores fluids, nutrients and waste.
cell wall
found outside the cell membrane in only plant cells and provides support for the cell
similarities plant vs animal cells
vacuoles, cell membrane, nucleus, mitochondria, cytoplasm, endoplasmic reticulum, ribosomes, golgi body
differences plant vs animal cells
vacuoles are noticeably bigger in a plant cell, plant cells have a cell wall and chloroplast
how does the shape of a plant cell differ from that of an animal cell?
a plant cell has a cell wall which helps it maintain a rigid structure whereas an animal cell has no cell wall
light microscope
uses light and a system of lenses to magnify the image
electron micropscope
an object is viewed using an electron beam instead of light. this allows us to see structures in far more detail
difference between light and electron microscope
electron microscopes allow us to see structures in far more detail than is possible using a light microscope
phospholipids
a fat-like substance, usually based on glycerol. Phospholipids are essential components of cell membranes. They are involved in the uptake of fats and fatty acids from the products of digestion
lipid bilayer
(or phospholipid bilayer) is a thin polar membrane made of two layers of lipid molecules. These membranes are flat sheets that form a continuous barrier around all cells.
transport proteins (carrier proteins)
a transport protein that changes shape when molecules bind to it, so that the molecules can pass through the plasma membrane. they take part in facilitated diffusion and active transport
channel proteins
a transport protein that molecules do NOT usually bind to. they allow specific molecules to pass through the plasma membrane, and are used in facilitated diffusion.
cholesterol
a steroid lipid found in most body tissues. it is an important component of cell membranes in animals and is used to form other steroid compounds.
plasma membrane structure
cholesterol, channel and carrier proteins, carbohydrate chain, glycoprotein, cytoskeleton filaments etc.
simple diffusion
Simple diffusion is the process by which solutes are moved along a concentration gradient in a solution or across a semipermeable membrane from a high concentration to a low concentration
facilitated diffusion
the process of spontaneous passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins. Being passive, facilitated transport does not directly require chemical energy
osmosis
the movement of water or other solvent through a plasma membrane from a region of low solute concentration to a region of high solute concentration, tending to equalise the concentrations of the solutes. Osmosis is passive transport, meaning it does not require energy to be applied.
active transport
the movement of molecules across a membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement.
hypertonic
refers to a solution with higher osmotic pressure than another solution. In other words, a hypertonic solution is one in which there is a greater concentration or number of solute particles outside a membrane than there are inside it
hypotonic
any solution that has a lower osmotic pressure than another solution. In the biological fields, this generally refers to a solution that has less solute and more water than another solution
isotonic
refers to two solutions having the same osmotic pressure across a semipermeable membrane. This state allows for the free movement of water across the membrane without changing the concentration of solutes on either side.
what are 3 ways to increase the cell surface area to volume ratio
- cell compartmentalisation
- a flattened shape
- plasma membrane extensions
Increasing the size of a cell will increase
membrane surface area but the volume of the cell
will also increase.
why are cells small
so that it helps the cells to maximise their efficiency in exchanging matter with their environment
what structures are visible to a light microscope
nucleus, cytoplasm, cell membrane, chloroplasts and cell wall. Mitochondria are also visible under light microscope but detailed study is not possible.
surface area: volume ratio
the cell is small (ratio) so that the surface area is bigger so the cell can receive more nutrients from the bigger SA
which shape has the highest SA:V ratio
any shape that is longer and thinner has a higher SA:V ratio than say a cube shape
Cells that have a high rate of metabolism would also need a
large surface area to volume ratio because Cells with a high rate of metabolism would need to exchange materials with their external environment rapidly and would therefore need a large surface area to volume ratio.
three structures are visible with a light microscope?
nucleus, vacuole, chloroplast
as a cell grows larger,
- the surface area
- what is a consequence to the cell
decreases
become less efficient in expelling wastes
what is a disadvantage of using an electron microscope
can’t view living specimen
what is an advantage of using a electron microscope
greater resolution and magnification
2 differences between eukaryotic and prokaryotic cells
prokaryotic cells are smaller (1-2ym) than eukaryotes
eukaryotes have a membrane-bound nucleus, prokaryotes don’t
2 functions of both common cell types
- both store water and nutrients (sustain life)
- both transport materials through the plasma membrane
ribosomes are found in both-
prokaryotic and eukaryotic cells
explain what is meant by the terms ‘fluid’ and ‘mosaic’ when describing the plasma membrane
fluid in fluid mosaic model refers to the fatty chains of the phospholipids that are like a thick, oily fluid. The term mosaic refers to the external surface that has various embedded proteins in the formation of a mosaic
explain how compartmentilisation aids the efficient functioning of eukaryotic cells
- increases SA:V
- optimal conditions established
- specialised conditions
- parts of cytoplasm seperate from cytosol
similarity and difference between simple and facilitated diffusion
- both passive processes (no ATP)
- simple - straight through phospholipid bilayer
- facilitated - through protein channels
what characteristic of water enables it to move through the lipid bilayer that forms the plasma membrane of a cell
water is polar, hence it is able to move through the lipid bilayer as it is also polar
- small, fit through gap
describe what might happen to a marine plant when placed in distilled water
the plant will absorb the water increasing and decreases the salt concentration
- plant cells become full or water - turgid
a biomacromolecule is
a large complex molecule-polymer made up of smaller units called monomers
lipids are NOT biomacromolecules because
they do not consist of repeating monomers
polar molecules
have a charge differential. This means they have a positively charged area and a negatively charged area
ions
are positively or negatively charged atoms
how a solute dissolves in h2o which is polar
each polar solute is either a positive or negative which attract one of the other. H2O has a positive and negative ion which each attracts to one of the other. the positive/negative ion pulls the opposite one away. This causes the solute to dissolve
what would happen if the solute was uncharged and mixed with water, why?
if the solute was uncharged and mixed with water, nothing would happen because there was no attraction to pull apart/dissolve
plasma membrane
acts as a boundary between the inside and outside of cells so that it can control what goes into the cell and what comes out of the cell
it’s an advantage for the membrane to be non-polar because..
- non-polar molecules are insoluble in water
- it will stay intact thus acting as a cell boundary
the membrane forms a bilayer (rather than a single layer) because..
- lipids are hydrophobic so they stay away from water
- it forms the two laters so that it is protected from water on the inside and outside of the cell
- the hydrophillic phosphates on the edges of the lipids act as a barrier between the water and lipids
diffusion
when particles spread out from an area of high concentration to low concentration. high - low is the concentration gradient. the process is passive as it doesn’t use energy.
SA:V high surface area:volume ratio characteristics
- would survive best in hot climates
- most efficient at removing wastes
- most efficient at exchange across cell membrane
SA:V low surface area:volume ratio characteristics
- would survive best in cold climates
- least efficient at exchange across membrane
- least efficient at removing waste
