Cell Structure and Function Flashcards
How thick is the Cell Surface Membrane?
7nm Thick
How many layers doe the cell surface membrane have?
3 layers
Purpose of cell surface membrane?
Partially permeable membrane controlling the exchange between the cell and its environment
what is the nucleus surrounded by?
2 membranes known as nuclear envelope
Features of Nuclear envelope
. tiny holes nuclear pores
contains loosely coiled chromosomes : Chromatin
Contains darker area : Nucleolus
Pores allow mRNA and ribosomes to leave and nutrients and hormones to enter
Functions of Nucleus
Controls cell activities
Chromosomes contain DNA
Nucleolus manufactures ribosomes
what is ER?
Endoplasmic Reticulum: extensive system of membranes forming flattened sacks called cisternae
Appearance of RER?
has ribosomes
Appearance of SER?
no ribosomes
Function of RER?
transport proteins made by ribosomes- makes Golgi Apparatus
Function of SER?
make lipids and steroids
Features of Ribosomes?
Free in cytoplasm or on ER
Size of Ribosomes?
22nm
What are ribosomes made of?
RNA and protein
Function of Ribosomes?
site of protein synthesis
Appearance of Golgi Apparatus?
stack of flattened sacks : Cisternae
How is Golgi Apparatus formed?
from vesicles that bud off from RER, broken down at other end to form Golgi vesicles
Function of Golgi Apparatus?
molecules collected, processed and stored especially proteins. taken from RER put into vesicles transported around and out of the cell
Used to make lysosomes
Appearance of Lysosomes
single membrane
0.1-0.5 micromertres
what do lysosomes contain?
Hydrolytic enzymes
Function of lysosomes?
Break down old organelles or cells e.g. white blood cells
How many membranes do mitochondria have?
2 called an envelope
why is the inner membrane of mitochondria folded?
To form projections called cristae
what’s the interior solution of the matrix called?
The Matrix
what are mitochondria involved in?
later stages of aerobic respiration
What do mitochondria make?
ATP involved in lipid synthesis
what are centrioles?
small hollow cylinders 0.4 micrometres in length
where are they found in animal cells?
next to the nucleus contain a ring of microtubules
what is the purpose of centrioles?
help form spindle in nuclear division
what is the cytoskeleton?
network of protein fibres
what does the cytoskeleton contain?
Actin filaments- microtubules made of tubulin around 25nm thick
also has proteins and microtubule motors using ATP
what is the purpose of the cytoskeleton?
provides cell strength
what does actin do?
helps the cell move e.g organelles and white blood cells
what do microtubules do?
move a microorganism through a liquid
what is the purpose of microtubule motors?
to move organelles
what is the cell wall made of?
Cellulose
what are plant cells linked by?
plasmadesmata - fine strands which pass through pores in plant cell walls
what is the vacuole surrounded by?
a membrane called tonoplast - fluid filledcontains mineral salts, sugars, oxygen, co2, and pigment
what does the tonoplast do?
controls the exchange of minerals between vacuole and cytoplasm
what is the purpose of the vacuole?
provide shape and support
how many layers does a chloroplast have?
2 called and envelope
what is inside a chloroplast?
jelly like substance - stroma
what do the membranes of a chloroplast do?
form flattened sacs called thylakoid membranes
stacked they are Grana
what is present in stroma?
starch grains and lipid droplets
purpose of chloroplasts?
for photosynthesis
two eukaryotic cells?
Animal + Plant
Contents of Animal cell?
Nucleolus, lysosome, chromatin, Golgi vesicle, Golgi Apparatus, Mitochondria, SER, RER, Nuclear Pore, Nuclear envelope, centrioles, ribosomes.
Contents of Plant Cell?
chloroplast, thylakoid, Golgi apparatus, Golgi vesicle, SER, cell wall, cell membrane, vacuole, tonoplast, ribosomes, RER, Nuclear envelope, chromatin, nuclear pore, mitochondrion
two hair like extensions on a cell used for movement?
Cilia + Flagella
what is Cilia?
many and short (
what is Flagella?
few and long, in eukaryotes they are undulapodia and move using ATP
what do cilia and flagella contain?
microtubules, nine pairs arranged in a circle
what is the arrangement of microtubules?
two in central bundle 9+2 arrangement
how do cilia and flagella move?
using ATP
what is flagella associated with?
locomotion
How does a sperm cell move?
Undulipodium forming a tail
what is a trichomonas?
a parasite with long whip tail
what is cilia associated with?
locomotion but sweeping motion
what does cilia move?
substances such as mucus across cell surface
what do cilia in bronchioles do?
sweeps mucus
purpose of cilia in oviducts
sweep egg along oviduct
Definition of magnification
the degree to which the size of an image is larger than the object its self
Definition of resolution
the degree to which it is possible to distinguish between two objects. the higher resolution the more detail
magnification of a light microscope
1500x
resolving power of light microscope
200nm
how do electron microscopes work?
use a beam of elcetrons: shorter wavelength than light
how does a TEM microscope work?
beam passes through a sample
how is the sample stored for TEM?
must be dead in a vacuum
what type of image does TEM produce?
2D
magnification of TEM microscope
500 000x
resolution of TEM microscope
0.2nm
how does SEM microscope work?
beam is reflected
what type of image is produced with SEM?
3D
Magnification of SEM
100 000x
resolution of SEM
0.2nm
how is sample stored for SEM
can be dead or alive
Magnification 0.01m
1x10^-2
what is staining?
a process helping to reveal features
what type of dye can be used in light microscopes?
fluorescent dyes
what are Acetic orcein stains used for?
DNA colours Dark Red
what dye is used for bacterial cell walls?
Gentian Violet
what stains are used in Electron microscopy?
Metal particles or salts
how are dyes added in electron microscopy?
by computer software known as false-colour
what does DNA contain?
instructions to make proteins
where is protein synthesised?
Ribosomes
where is protein transported?
through RER
what happens before protein travel towards Golgi apparatus?`
it is pinched off in a vesicle
what does the vesicle fuse to?
Golgi apparatus
what does the Golgi apparatus do with the protein?
processes and packages it ready for release
what happens after the packaged protein is pinched off?
it travels toward the plasma membrane
what does the vesicle fuse with?
plasma membrane
how does a protein leave a cell?
exocytosis