GCSE Combined Biology : Cells Flashcards
Nucleus
-Holds DNA of the cell
- is a plant cell and animal cell
cytoplasm
-chemical reactions take place here
- plant cell and animal cells
Cell Membrane
- controls what goes in and out of the cell
- plant and animal cell
Mitochondria
- where the cell does respiration which releases energy
- animal and plant cell
cell wall
- supports the cell , structure of plant ( made of cellulose)
-plant cell
vacuole
- place where the cell stores cell sap
- plant cell
chloroplast
- where plants make food ( photosynthesis )
- plant cell
ribosomes
small round structures in cytoplasm where cell makes clear jelly
- both animal and plant cells have it
required practical 1 : cheek slides :
what is the aim ?
to observe our cheek cells using a microscope
Required practical 1 : cheek slides :
method
1) firstly use a cotton swab to swab the inside of your cheek
2) Then transfer your cells to a slide , then dispose of the cotton bud
3) Add one drop of Methylene blue and place the coverslip using a mounted needle
4) using a tissue / paper towel carefully cover the slide to get rid of necessary Methylene. After that you can look at your specimen using a microscope
Required practical 1 : cheek slides :
method
1) firstly use a cotton swab to swab the inside of your cheek
2) Then transfer your cells to a slide , then dispose of the cotton bud
3) Add one drop of Methylene blue and place the coverslip using a mounted needle
4) using a tissue / paper towel carefully cover the slide to get rid of necessary Methylene. After that you can look at your specimen using a microscope
required practical 1 : cheek cells
observations
You could see black dots on my specimen , using 40 x lens allowed me to see the cells / make them visible
required practical 1 : cheek cells
equipment list
- Methylene blue
-slide
-cotton swab - mounted needle
-coverslip
-microscope
-tissue
parts of a microscope
- eyepiece
- body
- nose
- objective lenses
- stage clips
-iris - light + mirror
-stage - coarse focusing wheel
- fine focusing wheel
-base
parts of a microscope
- eyepiece
- body
- nose
- objective lenses
- stage clips
-iris - light + mirror
-stage - coarse focusing wheel
- fine focusing wheel
-base
what is a stem cell
a cell that hasn’t yet become specialised.Stem cells are able to turn into many different cell types
2 types of stem cells
1.stem cells found in embryos are known as embryonic stems cells and can develop into almost every cell
2. Stem cells found in bone marrow are known as adult stem cells and can only change into a few cell types
Q. evaluate the advantages and disadvantages of stem cell research (6marks)
ADVANTAGES
- Embryos are being created from adult cells for use in therapy , they would never become babies
- embryos are mostly spare embryos left from IVF treatment which would be destroyed anyway
- stem cells could be used to treat paralysis Alzheimer and diabetes
DISADVANTAGES
- takes a long time to develop
-All embryos could become babies, therefore it is unethical to test on them
- Embryos cannot give permission to be used , it is unethical
- Embryonic stem cell treatment is experimental and there is a risk that they may cause problems such as cancer
main parts of animal and plant cells
- Nucleus
-mitochondria
-cell membrane
-cytoplasm
-ribosomes
What does Eukaryotic mean
with nucleus ( humans )
- Plant cells + animal cells
what does prokaryotic
before nucleus/ without nucleus ( bacteria )
- Bacteria and Archaea
Bacteria are amongst the simplest of organisms - they are made of single cells. Their cell structure is simpler than the cells of eukaryotes and cells are smaller, most are 0.2 μm - 2.0 μm. These cells do not contain membrane bound organelles such as a nucleus and mitochondria. contains DNA , flagellum, capsule
Structure of how to answer this question
Q. Compare Eukaryotic and Prokaryotic cell structure ( include functions )
(6marks)
- define what Eukaryotic and prokaryotic is
- similarities : both have cytoplasm , cell membrane , mitochondria , ribosomes , cell wall
- differences : prokaryotic has DNA , flagellum/a , capsule
-functions ( from prokaryotic and eukaryotic
what is a microscope used for
to see small objects better , it magnifies the object so that you can see cells etc
why is a microscope useful
helps us see whats inside an object , which helps for research to make cures. etc
resolution
ability to see 2 points as 2 points , rather than merged into oen
light microscope
MAGNIFICATION : 1500x
RESOLUTION : 0.2um /200nm - cannot distinguish 2 points closer than 200nm
PROS : you see parts of cell; such as nucleus, chloroplasts etc , it is cheaper and can be used in classroom
CONS ; you cant see parts of cell in detail such as mitochondria , ribosomes
Electron microscope
Magnification: maximum 1,000,000x
Resolution: transmission electro microscope is now less than 1nm
Pros : You can see inside of parts of cells/organelles (nucleus=DNA) . Very detailed
Cons : The cells have to be dead as it goes in a vaccine , expensive (3million). Microscope is very large( only available in universitys/labs )
compare Light microscope and electron microscope
- Electron microscope has a higher magnification ( will look bigger)
-electron microscope has higher resolution
-Electron microscope is more detailed - light microscopes are more portable but less detailed
-electron microscopes are more expensive
how will you want to calculate the size of an object
under a microscope
what is the formula for magnification
Magnification = image size / actual size.
Actual size = image size / magnification.
image size=magnification x real size