cell structure and division Flashcards
what are eukaryotic cells
complex cells, incluse all animal and plant cells, algae and fungi
animal cell organelles
1) plasma (cell membrane) surface
2) rough endoplasmic reticulum
3) smooth enodplasmic reticulum
4) nucleolus
5) nucleus
6) lysosome
7) nuclear envelope
8) golgi appratus
9) mitochondria
10) cytoplasm
11) ribosome
plant cell organelles
1) plasma (cell membrane) surface
2) rough endoplasmic reticulum
3) smooth enodplasmic reticulum
4) nucleolus
5) nucleus
6) lysosome
7) nuclear envelope
8) golgi appratus
9) mitochondria
10) cytoplasm
11) ribosome
12) chloroplast
13) plasmodesmata
14) vacuole
15) cell wall
algae cells
1) plasma (cell membrane) surface
2) rough endoplasmic reticulum
3) smooth enodplasmic reticulum
4) nucleolus
5) nucleus
6) lysosome
7) nuclear envelope
8) golgi appratus
9) mitochondria
10) cytoplasm
11) ribosome
12) chloroplast
13) plasmodesmata
14) vacuole
15) cell wall
fungal cells
1) plasma (cell membrane) surface
2) rough endoplasmic reticulum
3) smooth enodplasmic reticulum
4) nucleolus
5) nucleus
6) lysosome
7) nuclear envelope
8) golgi appratus
9) mitochondria
10) cytoplasm
11) ribosome
12) plasmodesmata
13) vacuole
14) cell wall (made of chitin)
cell surface-membrane
found on surface of animal calls, and inside cell wall of other cells, made of lipids and proteins
cell surface-membrane function
regulates movement of substances into and out of the cell, has receptor molecules so it can respond to hormones
nucleus
surrounded by nuclear envelope, contains chromosomes and the nucleolus
nucleus function
controls cells activities
nuclear envelope
surrounds nucleus, contains pores
nuclear envelope function
controls what enters and leaves the nucleus
nucleolus
found inside nucleus
nucleolus function
makes ribosomes
mitochondrion
found in large numbers in active cells, oval shaped, have double membrane (inner one is folded to form crista) inside = matrix
mitochondrion function
site of aerobic respiration, where ATP is produced
matrix
contains enzymes involved in respiration
chloroplast
flattened structure, surrounded by double membrane, contains thylakoid membranes
chloroplast function
site of phototosyntheses
thylakoid membranes
stacked up inside chloroplast to form grana (which are linked by lamellae)
lamellae
thin, flat pieces of thylakoid membrane
golgi apparatus
group of fluid filles membrane bound flattened sacs, often containing vesicles on the edges
golgi apparatus function
processes and packages new lipids and proteins, and makes lysosomes
golgi vesicles
small, fluid filled sac in cytoplasm surrounded by membrane and produced by golgi apparatus
golgi vesicle function
sotres lipids and proteins made by the golgi apparatus and transports them out of the cell
lysosome
round organelle surrounded by a membrane, with no clear internal structure (type of golgi vesicle)
lysosome function
contains digestive enzymes called lysozomes which are used to digest invading cells/break down worn out components of the cell
ribosome
very small organelle that either floats free or is attached to the rough endoplasmic reticulum, made up o proteins and RNA (not surrounded by membrane)
ribosome function
site where proteins are made
rough endoplasmic reticulum (RER)
membranes enclosing a fluid filled space, covered in ribosomes
rough endoplasmic reticulum (RER) function
folds and processes proteins (that have been made at the ribosomes)
smooth endplasmic reticulum (SER)
membranes enclosing a fluid filled space
smooth endplasmic reticulum (SER) function
synthesises and processes lipids
cell wall
rigid structure that surrounds cells (plans & algae = made of cellulose, fungi = made of chitin)
cell wall function
supports cell, stops it from changing shape
cell vacuole
found in cytoplasm (of plant cell) contains cell sap, surrounded by membrane called tonoplast
cell vacuole function
helps to maintain pressure and keep the rigid (stops plant from wilting), involved in the isolation of unwanted chemicals inside cell
what is cell sap
weak solution of sugar and salts
what are specialised cells
cells specialised to carry out a specific function (e.g epithelial cells in small intestine are specialised to absorb food efficiently - villi and microvilli)
what are tissues
a group of specialised cells working together to perform a specific function
what are organs
a group of tissues working together to perform a specific function
what are organ systems
a group of organs working together to perform a specific function
what are prokaryotic cells
smaller, simpler cells (e.g bacteria)
prokaryotic cells organelle
1) cytoplasm
2) plasma membrane
3) cell wall
4) flagellum
5) DNA
6) plasmids
7) capsule
prokaryotic cytoplasm
has no membrane bound organnelles, it has small ribosomes
prokaryotic plasma membrane
controls the movement of substances into and out of the cell
prokaryotic cell wall
supports the cell wall and prevents it changing shape, made from murien (polymer thats a glycoprotein)
what is a glycoprotein
protein with a carbohydrate attached
prokaryotic flagellum
long, hair-like structure that rotates to move the cell (not all have one, some cells have multiple)
prokaryotic DNA
floats free in the cytoplasm, not attached to histone proteins, circular
prokaryotic plasmids
small loops of DNA that contain genes for things like antibiotic resistanc, can be passed between prokaryotes ( not always present, some have multiple)
prokaryotic capsule
made up of secreted slime, helps protect bacteria from attack cells in the immune system
what are virus’
small, acellular (nucleic acids surrounded by protein)
virus replication
invade and reproduce inside the cells of other organisms (host cells)
how virus’ replicate
1) use their attachment proteins to bind to complementary receptor proteins on surface of host cells (different receptor proteins on each virus=can only infect one type of cell)
2) inject their DNA/RNA into the host cell and hijacks it, so the cells replicate the viral particles for them
virus structure
core of genetic material (DNA or RNA), protein coat around core (capsid), attachment protein (stick out from edge)
prokaryotic cell replication
binary fission
binary fission
cell replicates before splitting into 2 daughter cells
binary fission process
1) circular DNA and plasmids replicate(DNA= once, plasmids = lots of times)
2) cell gets bigger, DNA loops move to opposite poles
3) cytoplasm begins to divide, new cell walls form
4) cytoplasm divides into 2 daughter cells, each has 1 copy of DNA and variable number of plasmids
magnification
how much bigger the image is than the specimen
magnification calculation
size of image divided by size of real object
resolution
how well a microscope distinguishes between two points that are close together (how detailed the image is)
types of microscope
optical (light) and electron
optical (light) microscope
use light to form an image, max resolution of 0.2micrometres (can’t view anything smaller, e.g ribosomes, RER, SER, lysosomes etc), max magnification is x1500
electron microscope
use electrons to form an image, higher resolution of about 0.0002micrometres, max magnification of x1500000 (because electron waves are smaller than light waves)
micrometres to millimetres
divide by 1000
types of electron microscope
transmission (TEM) scanning (SEM)
transmission electron microscope
use electromagnets to focus a beam of electrons, which is then transmitted through the specimen, denser parts absorb more electrons so look darker on the final image
TEM advantages
give high resolution images, so you can see the internal structure
TEM disadvantages
can only be used on thin specimens
scanning electron microscope
scan a beam of electrons across a specimen which knocks off electrons from the specimen, and they are gathered in a cathode ray tude to form an image
SEM advantages
gives the surface of the specimen, can be 3D, can be used on thick specimens
SEM disadvantages
give lower resolution images
preparing a slide for opital microscope
1) pipette a small drop of water onto slide
2) use tweezers to place a thin specimen on top of the water droplet
3) add a drop of stain to highlight objects (e.g iodine in porassium iodide solution used to stain starch grains in plants)
4) add cover slip by placing upright next to specimen, then tilting slowely being careful to not trap airbubbles
cell fractionation
seperates organelles
cell fractionation stages
homogenisation, filtration, ultracentrifugation
homogenisation
breaking the cells apart e.g by vibrating the cells/grinding cells in a blender (which breaks up the plasma membrane and released organelle into solution)
homogenisation solution
solution should
1) be ice cold (to reduce activity of enzymes that break down organelles)
2) be isotonic (to stop damage to organelles through osmosis)
3) contain a buffer solution (to maintain pH)
what does isotonic mean
has the same concentration of chemicals as the cells being broken down
filtration
solution is filtered through a gauze to seperate large cell debris/ tissue debris (e.g connective tissue) from the organelles
ultracentrifugation
seperates the organelles
ultracentrifugation method
1)cell fragments are poured into a tube
2)tube is placed into centrifuge and spun at low speed
3)heaviest organelle (e.g nucleus) get flung to the botttom and form a thick sediment called the pellet
4)other organelles stay suspended in fluid above the sediment, called supernatant, are drained off and put into another tube, put into centrifuge and spun at a higher speed
5)heaviest organelles go to bottom (mitochondria) to form a pellet
6) method repeated until all organelles seperated out
tube is made up of heaviest - lightest organelles
what is the pellet
thick sediment of heaviest organelle at the bottom of centrifuge tube
what is the supernatant
organelles suspended in solution above the pellet in the centrifuge
mitosis
cell division that produces genetically identical cells, used for growth and repair
mitosis stages
interphase, prophase, metaphase, anaphase, telophase
interphase
before cell cycle, DNA is unravelled and replicated, organelles are replicated, ATP content is increased
prophase
first stage, chromosomes condense (getting shorter and fatter), centrioles move to opposite poles, spindle fibres form across the cell, nuclear envelope breaks down, chromosomes like free in cytoplasm
metaphase
second stage, chromosomes line up along the middle and become attached to spindle fibres by their centromere
anaphase
third stage, centromeres divide (seperating sister chromatids), spindle fibres contract pulling chromatids to opposite poles of the spindle centromere first (makes chromatids v-shaped)
telophase
final stage, chromatids reach opposite poles on spindle, uncoil and become thin and long again (are called chormosomes again), nuclear envelope forms to form 2 nuclei, cytoplasm divides (cytokinesis) to form 2 genetically identical daughter cells
what is cancer
result of uncontrolled mitosis (cells keep growing and form a tumor)
cancer treatments designed to target cell cycle
G1 (growth and protein production) - chemotherapy prevents synthesis of enzymes needed to replicate
or S phase (DNA replication) - radiation damages DNA which causes cell to kill itself, stopping replication
mitosis cell cycle
G1 (gap phase 1), S (synthesis) , G2 (gap phase 2), M (mitosis)
G1 - gap phase 1
cell grows and new organelles and proteins are made
S - synthesis
cell replicates its DNA ready to divide during mitosis
G2 - gap phase 2
cell keeps growing and proteins needed for cell division are made
M - mitosis
cycle starts and ends here
