cells Flashcards
describe the cellulose cell wall
plant cell
- tough, non living, freely permeable layer made of cellulose surrounding the membrane
- provides strength to the cell
- prevents plant cells from bursting
- allows water and dissolved substances to pass through freely
permanent vacuole
plant cell
- contains cell sap
- found within the cytoplasm
- improves cells rigidity: watery sol. helps maintain shape + firmness of cell
- can store salts and sugars
- fluid filled space containing dissolved substances, surrounded by a membrane
chloroplasts
plant cell
- organelle containing chlorophyll
- inside cytoplasm of some plant cells
- where photosynthesis takes place, providing food for the plant
- converts light energy -> chemical energy stored
in molecular bonds of glucose
- plant uses the glucose molecules to create
complex carbohydrates -- starch and cellulose --
and other nutrients that it needs to grow and
reproduce.
- contains chlorophyll pigment (which makes it green) which harvests the light needed for photosynthesis
define eukaryotic
eukaryotic Eukaryotes are organisms made up of cells that possess a membrane-bound nucleus that holds genetic material as well as membrane-bound organelles. - cell membrane - cytoplasm - nucleus containing the DNA
nucleus
plant and animal
- controls cell division and development
- controls the activities of the cell
- inside cytoplasm
- contains DNA (in the form of chromosomes) coding for a particular protein needed to build new cells
- enclosed in a nuclear membrane
cytoplasm
plant and animal
- enclosed by cell membrane
- contains dissolved substances, particles and organelles
- liquid jelly-like substance in which chemical reactions occur
- contains enzymes (biological catalysts, ie. proteins that speed up the rate of reaction)
cell membrane
plant and animal
- partially permeable layer
- forms barrier around cytoplasm
- controls what enters and leaves the cell
- separates cell contents from the surroundings and keeps the contents from escaping
mitochondria
plant and animal
- where aerobic respiration reactions occur, providing energy (as ATP) for the cell
- each mitochondrion has double membrane, outer one controls entry and exit of materials
- inner has many folds on which some chemical reaction of aerobic respiration take place
ribosomes
plant and animal
- where protein synthesis occurs
- found on a structure called the rough endoplasmic reticulum
what structures are in bacterial cells
they are prokaryotic so they have
- cytoplasm
- cell membrane
- cell wall made of peptidogylcan
- singular strand of DNA (no nucleus, floats in the cytoplasm)
- plasmids- small rings of DNA
which small organelles are located in the cytoplasm (just list them)
include: mitochondria vesicles ribosomes rough endoplasmic reticulum
what do the cytoplasm of all cells contain
the cytoplasm of all cells contains vesicles and ribosomes on rough endoplasmic reticulum
rough endoplasmic reticulum
endoplasmic reticulum (ER) is a complex system of parallel membranes running throughout the cell
linked with both cell and nuclear membranes
contain fluid-filled spaces between the membrane -> allows materials to be transported throughout the cell
Rough ER is covered with ribosomes which make protein for the cell (main function of rough ER is to package + transport proteins)
cells that produce a lot of protein (eg. making digestives enzymes in alimentary canal -> large amounts of rough ER
small vesicles formed when small pieces of rough ER are pinched of at the ends
- proteins can be made and stored in rough ER, transported around cell in small vesicles
what do almost all cells, except prokaryotes have?
(almost) eukaryotic cells have mitochondria and rough ER
why would cells require large numbers of mitochondria
cells with high rates of metabolism require large numbers of mitochondria to provide sufficient energy
ribosomes
small organelles found in huge number in all cells
- 20 nm diameter in eukaryotic cells
- smaller in prokaryotic (free in cytoplasm, not attached to rough ER)
- function: synthesise proteins, eg those enzymes involved in respiration
how do you calculate the size of cells and specimens
actual size= image size ÷ magnification
M= I/A
Ribosomes on ___ and in the ___ make ___
Rough ER ___ and transports ___
___ respiration occurs in ___
Cells with high rates of respiration have ___ ___
Ribosomes on rough ER and in the cytoplasm make proteins
Rough ER packages and transports proteins
Aerobic respiration occurs in mitochondria
Cells with high rates of respiration have many mitochondria
define tissue
a group of cells with similar structures, working together to perform a shared function
define organ
structure made up of a group of tissues, working together to perform specific functions
define organ system
group of organs with related functions, working together to perform body functions
describe ciliated cells
found in air passages in lungs (trachea and bronchi) and oviducts in the female reproductive system
- cells have cilia on the surface, cilia beats back and forth to create a current in the fluid next to the cell surfaces
- airways: cilia move the mucus that traps dust and pathogens up to the nose and throat
- oviducts: cilia move the egg from the ovary to the uterus
root hair cells
specialised to take up water by osmosis and mineral ions by active transport from the soil
found in the tips of the roots
- large SA, due to long extensions of root hairs, meaning more water can move in
- large permanent vacuole affects speed of movement of water from soil to cell
- mitochondria for energy from respiration for active transport of mineral ions into the root hair cell
xylem cells
specialised to transport water and mineral ions up the plant from the root to the shoots
- cell walls thickened with bands/spirals of cellulose and lignin
- upon formation, a chemical called lignin (water-proof) is deposited which causes the cells to die
- they become hollow and are joined end-to-end to form a continuous tube so water and mineral ions can move through
- lignin is deposited in spirals which helps the cells withstand the pressure from the movement of water
- cells help to support the stems and leaves
nerve cells
specialised to transmit electrical signals quickly from one place in the body to another
- has thin extensions of cytoplasm like wires
- long axon, enabling the impulses to be carried along long distances
- lots of connections from the cell body (dendrites) means branched connections can form with other nerve cells
- nerve ending have many mitochondria which supply the energy to make special transmitter chemicals called neurotransmitters -> these allow the impulses to be passed from one cell to another
red blood cells
specialised to transport oxygen for aerobic respiration.
- absorb oxygen in the lungs, pass through narrow blood vessels, and release oxygen to respiring cells.
- contain haemoglobin - a red protein that combines with oxygen
- no nucleus so they can contain more haemoglobin
- they are small and flexible so that they can fit through narrow blood vessels
- they have a biconcave shape (flattened disc shape) to maximise their surface area for efficient oxygen absorption
palisade mesophyll cells
specialised for photosynthesis
- numerous chloroplasts in cytoplasm which trap light energy for photosynthesis
- has cell wall made of tough cellulose which strengthens the cell
- cytoplasm has large vacuole filled with cell sap
- starch grains inside cytoplasm formed by photosynthesis and temporarily store energy
sperm cells
specialised to carry the males DNA to the egg cell (ovum) for reproduction
- streamlined head and long tell to aid swimming
- many mitochondria (where respiration happens) which supply the energy to allow the cell to move
- the acrosome (top of the head) has digestive enzymes which break down the outer layers of membrane of the egg cell
egg cells
specialised for reproduction
- contain yolk as a store of energy
- genes of the mother found inside nucleus of the egg
- cytoplasm contains nutrients for the growth of the early embryo
- haploid nucleus contains the genetic material for fertilisation
- cell membrane changes after fertilisation by a single sperm so that no more sperm can enter
- one of the biggest cells in the body and only a few are made.
define prokaryotic
Prokaryotes are organisms made up of cells that lack a cell nucleus or any membrane-encased organelles.
- cell wall
- cell membrane
- cytoplasm
- single circular strand of DNA and plasmids (small rings of DNA found in the cytoplasm)
define nutrition
taking in of materials for energy, growth, and development;
plants require light, carbon dioxide, water and ions
animals need organic compounds and ions and usually need water
define movement
an action by an organism or part of an organism causing a change of position or place
define respiration
the chemical reactions in cells that break down nutrient molecules and release energy for metabolism
define sensitivity
sensitivity is the ability to detect or sense stimuli in the internal or external environment and to make appropriate responses
define growth
growth is a permanent increase in size and dry mass by an increase in cell number or cell size or both
define excretion
the removal from organisms of the waste products of metabolism (chemical reactions in cells including respiration), toxic materials and substances in excess of requriements
what is the most common microscope used in schools called
what are the ones with 2 eyepieces called
monocular light microscope
2 eyepiece- binocular or compound light microscopes
give examples of an organism that contains eukaryotic cells
animal, plants, fungi, protists
give examples of an organism that contains prokaryotic cells
bacteria, archaea
what are vesicles, how do they look like on an animal cell
vesicles are small structures within the cell that consists of fluid enclosed by a lipid bilayer involved in transport, buoyancy control and enzyme storage
looks like a small circle near the cell membrane
state some distinguishing features of all prokaryotes
- they are unicellular
- they have no true nucleus but rather a loop of DNA
- no membrane-bound organelles
- reproduce by binary fission
- smaller ribosomes
