cell biology Flashcards
(24 cards)
what are the features of plant and animal cells?
they both have cell membranes, ribosomes, mitochondria, nucleus and cytoplasm .
plant cells also have a cell wall, large vacuole and chloroplasts.
what are the functions of the organelles in plant and animal cells?
nucleus: stores genetic info/DNA
cell membrane: controls what comes in and out of the cell
cell wall: keeps a fixed, strong structure
mitochondria: releases energy through respiration
ribosomes: make proteins for growth and repair
cytoplasm: site of chemical reactions and anaerobic respiration
vacuole: stores cell sap
chloroplasts: site of photosynthesis
how is an egg cell adapted for its function?
contains a lot of cytoplasm which has the nutrients for the growth of the early embryo
haploid nucleus contains genetic material for fertilisation
cell membrane changes after fertilisation so no other sperm can enter
how is a sperm cell adapted for its function?
a tail to move them towards the egg
many mitochondria to provide them with energy
an acrosome that releases enzymes to digest the egg membrane
how is a red blood cell adapted for its function?
bi concave shape which maximises their surface area to absorb oxygen
they have a thin membrane so gases can easily diffuse through
no nucleus so they contain more heamaglobin which bind to oxygen
how is a white blood cell adapted for its function?
some have cytoplasm which can flow making it possible to for the cell to change shape, surround and engulf bacteria
they have an irregular shape so they can change shape to squeeze out of blood vessels and get to site of infection
large nucleus helps to produce antibodies
how is a nerve cell adapted for its function?
they are adapted to carry electrical impulses from one place to another
they have an axon which is a single nerve fibre that carries nerve impulses away from a cell body which is insulated by a myelin sheath
dendrites are branched nerve fibres which receive nerve impulses and pass them towards the body
longest cell
how is a muscle cell adapted for its function?
muscle cells have many mitochondria which provides them with energy for movement
they also have muscle fibres which can contract and relax to change the shape of the cell.
how is a root hair cell adapted for its function?
have a long root hair the gives them a large surface area for absorption of water and minerals
large permanent vacuole stretches into the root hair cell and this speeds up the movement of water by osmosis from the soil across the cell
many mitochondria transfer the energy needed for active transport of minerals irons into the root hair cell
how is a ciliated epithelial cell adapted for its function?
they have many cilia which provides a large surface area to sweep mucus along.
the mitochondria provide energy to help the cilia
what is the difference between a prokaryotic and eukaryotic cell?
a eukaryotic cell is a cell tat has a nucleus wrapped in a membrane (true nucleus)
a prokaryotic cell does not have a nucleus- the DNA is free in the cytoplasm
eukaryotic cells are bigger then prokaryotic cells
name the organelles in a typical bacteria cell
cell wall, cell membrane, flagella, plasmids, strand of DNA
what is the equation for magnification?
magnification= image size/size of the real object
what are stem cells?
stem cells are undifferentiated cells and they have the ability to become any type of specialised cell in the body, there are also many stem cells in different parts of a plant called meristem cells so it is possible to make a completely new plant from just a small part or a few cells
what are the two types of human stem cells?
adult stem cells and embryonic stem cells
why are there ethical issues with using embryonic stem cells?
people will believe that the egg cell is already living and many religions believe that it has the potential for human
what is mitosis?
mitosis is how new cells are made; it is a kind if nuclear division for producing new body cells for growth and repair of body tissue and asexual reproduction
describe the steps of mitosis
1) the DNA and organelles are growing
2) the chromosomes and organelles are copied
3) the chromosomes line up at the middle (equator) of the cell
4) the chromosomes are pulled apart and they begin to divide
5) the chromosomes have divided and cell membranes and nuclear membranes are formed
6) the two nuclei are formed and this produces two genetically identical daughter cells
what is diffusion?
diffusion is when particles move from an area of higher concentration to an area of lower concentration, they move along a concentration gradient
what four things can help with diffusion?
1) a massive surface area
2) a lining that is only one cell thick
3) a very good blood supply
4) moist surface
how can diffusion be accelerated?
it can be accelerated by either increasing the concentration of the particles which would make them move faster or by increasing the concentration gradient of the substance that is diffusing
what is osmosis?
osmosis is the movement of water through a partially permeable membrane from a dilute solution to a concentrated solution, it is a passive process
describe active transport
a molecule is transported across the cell membrane through the carrier protein, energy from respiration is used to change the shape of the carrier protein, the molecule is released on the other side of the protein, the carrier protein goes back to its original shape
(molecules can only be transported across the membrane in one direction and against the diffusion gradient)
what makes a good exchange surface?
- be moist
- large surface area
- thin
- well ventilated (for gaseous exchange)
- have a good turnover of molecules (for digestion)
- animals-large, efficient blood supply
