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
Keypoint
Light microsocopes magnify up to about x2000 and have a resolving power of about 200nm
Keypoint
Electron microscopes magnify up to about x2,000,000 and have a resolving power of around 0.2nm
Keypoints
in body cells , chromosomes are found in pairs. Body cells divide in a series of stages called the cell cycle. during the cell cycle the genetic material is doubled , it then divides into 2 identical nuclei in a process called mitosis. before a cell can divide it needs to grow, replicate the DNA to form 2 copies of each chromosome and increase the number of subcellular structures.In mitosis one set of chromosomes is pulled to each end of the cell and the nucleus divides. Finally the cytoplasm and cell membranes divide to form 2 identical cells . mitotic cell division is important in the growth , repair ,and development of multicellular organisms.
what is cell division by mitosis used for ?
to produce the additional cells needed for growth and development in multicellular organisms , and for replacement of worn out or damaged cells
what is mitosis
Mitosis is the process by which a cell replicates its chromosomes and then segregates them, producing two identical nuclei in preparation for cell division. Mitosis is generally followed by equal division of the cell’s content into two daughter cells that have identical genomes.
where does Gas exchange occur
in alveolis
aerobic respiration word equation
aerobic respiration = oxygen + glucose = water + carbon dioxide +(energy)
difference between magnification and resolution
resolution is the ability to see 2 points as 2 points rather than merged into one. Magnification changes how close or far you see the specimen
what does magnification measure
how much bigger an object appears in microscope
formula for total magnification
total magnification = eye piece x objective lens
μm
micrometres
what is cm = mm
what is mm = μm
cm=mm (x10 )
mm= μm(x100)
why do cells need to divide
- reproduction
- heal / repair
-growth
apoptosis
cell self destroys itself before it divides if doesnt do functions correctly
homo
some
how many chromsomes
46 chromosomes (23pairs)
one from other and one from father
chromosomes are piece of DNA that contains gas.
A cell that has pairs of chromosomes is set to be diploid
cell that has single chromosomes (sperm and egg cells ) are set to be haploid
what does a chromosome contain
the location (locus) of thousands of genes. for each species you will find the same gene at the same locus , although it may be a different version of that gene (allele) e.g brown eyes and blue eyes
keypoint
cancer cells pass checkpoint , do mitosis very often , and multiply a lot
cell cycle
series of events that take place during cells life, as it grows and divides
what causes cancer
uncontrolled cell growth
what things happen during interphase of the cell cycle
-growing
-replication DNA
-Cell function
what percentage of cells life is spent
90%
what is mitosis
-dividing making new cells
- important to generate new cells
-helps for healing
what is a cell checkpoint
-check that cell is growing correctly, does right functions correctly before they divide
Apoptosis= cells self destroys itself before it divides
what types of cells does chemotherapy target
cells that go through mitosis/growth quickly hair falls out because hair cells are fast growing
6 stages of mitosis
- Prophase
Chromosomes condense. They get shorter and the nucleus membrane breaks down – this releases the chromosome into the cytoplasm. - Metaphase
Chromosomes line up on the equator. Chromosomes line up on the equator (middle) of the cell.
3. Anaphase
Chromosomes are pulled to opposite poles of the cell. The separate ends of the cells are called the poles. The chromosomes are pulled to the poles by spindle fibres.
4. Telophase
Two new nuclei form. New membranes are built around these chromosomes, so they become new nuclei. This means that the nucleus has divided into two.
what is diffusion
movement of particles from area of high concentration to an area of low concentration
diffusion only occurs in……………..
fluids which are liquids and gas
Diffusion
solvent moves by concentration gradient
when does diffusion stop
when they reach equillibrium ( particles stop. fully diffuse
factors affecting diffusion
-concentration gradient = difference between concentrations
- temperature
-length of diffusion pathway (distance particles must travel )
Q. compare the diffusion of a tea bag in hot water and one in cold water (6marks )
- both glasses have same amount of water and have same teabags
-One glass has warm water whereas the other has cold
-The teabag dissolved quicker in hot water than cold , - there is a short diffusion pathway as the material is thin.
-High temperature = faster diffusion - low concentration in water
high concentration
lots of particles
low concentration
small amount of particles
solvent
substance in which other substances dissolve
solute
a substance that can dissolve
solution
a mixture formed when a solve dissolves in a solvent
what is osmosis
movement of water molecules from an area of higher water concentration to an area of lower water concentrations, through a partially permeable membrane
how is osmosis different do diffusion
osmosis only occurs in liquids , whereas diffusion occurs in liquids , whereas diffusion occurs in gases and liquids. Also osmosis requires a permeable membrane whereas diffusion does
what is hypotonic
having a lower osmotic pressure than a particular fluid, typically a body fluid or intracellular fluid.
hypertonic
A solution will be hypertonic to a cell if its solute concentration is higher than that inside the cell, and the solutes cannot cross the membrane. If a cell is placed in a hypotonic solution, there will be a net flow of water into the cell, and the cell will gain volume.
isotonic
An isotonic solution is any external solution that has the same solute concentration and water concentration compared to body fluids. In an isotonic solution, no net movement of water will take place
describe what happens in
-hypertonic condition
-isotonic condition
-hypotonic condition
Hypertonic condition :
higher concentration in the cell and low concentration out of the cell because in osmosis water goes from high c to low c
Hypotonic condition:
higher concentration out of the cell as water goes into the cell - cell has lower c
isotonic condition :
same amount of concentration as it goes in and out of cell.
required practical :osmosis
equipment
- a potato
- a cork borer / potat chipper
- ruler
-10cm^3 measuring cylinder - pen to write on glass
-five boiling tubes - test tube rack
-paper towels
-a sharp knife - a white tile
- distilled water
-range of sugar solutions (0.25m , 0.5m 0.75m,1.0M - a top-pan balance
required practical : osmosis
what was the point?
to see change in mass of potato cylinder using osmosis
