Cells Flashcards
What is the site of respiration?
Mitochondria
How to measure magnification in a microscope ?
Magnification = size of image / size of real object
What is the function of the cell membrane?
It is selectively permeable which forms a boundary for the cell and controls what enters and leaves
What is the function of the nuclear membrane?
Surrounds the nucleus
What is the function of cytoplasm?
Where chemical reactions take place
What is the function of the nucleus (A.K.A. Control centre of the cell)?
This contains chromosomes and genetic information for the cell
What is the function of chromosomes?
Found in the nucleus. Made up of the molecule DNA which contains the genetic information for the organism
What is the function of the cellulose cell wall?
Stiff structure just outside of the membrane that provides support
What is the function of the chloroplast?
Contain chlorophyll which traps light used in the process of photosynthesis. Only found in the green parts of the plant
What is the function of the Large Permanent Vacuole
Contains cell sap
that when full pushes the cell membrane against the cell wall making the cell more rigid which provides more support
What is a stem cell?
Stem cells are simple cells in animals and in plants that has the ability to divide to form more cells of the same type
Where can stem cells be harvested from in animal cells?
In animals stem cells can be harvested from (embryonic) umbilical cord or bone marrow (adult)
What is the difference between embryonic stem cells and adult stem cells?
Embryonic stem cells form a full range of cell types while adult stem cells form a limited range of cell types
What do most animal stem cells change permanently into?
Most stem cells change permanently at an early stage into specialised cells with structures that adapt them to a particular function
What do plant stem cells originate from?
In plants, stem cells originate from meristems at the apices of the root and stems and many of these cells retain the ability to divide and so can be used in cloning techniques
What potential benefits come from using stem cells in medicine?
Bone marrow transplant in treating leukaemia
What are the potential risks in using stem cells in medicine?
Ethical implications, including pre-treatment using radiotherapy or chemotherapy, transfer of viruses or diseases from other animals, formation of tumours or development of unwanted cell types
What is there not in bacteria cells that are in plant and animal cells?
There is no cellulose cell wall but there is a non-cellulose cell wall, absence of nucleus but there is presence of plasmids in the bacterial cell
What can multicelled organisms’ form
Multicelled organisms’ can form specialised tissues, organs and organ systems
Why do multicelled organisms need a exchange surface? (eg alveoli in the lungs)
Surface area affects the rate at which particles can enter and exit the cell
Volume affects the rate at which materials are made or used within the cell
As the volume of the cell increases, so does the surface area, but not to the same extent. When the cell gets bigger its surface area to volume ratio gets smaller
And if the surface area to volume ratio gets too small:
Substances won’t be able to enter the cell fast enough to fuel the reactions.
Waste products will start to accumulate within the cell as they will be produced faster than they can be excreted
Cells will not be able to lose heat fast enough and so may overheat
This is why multicelled organisms need an exchange surface.
In addition, a transport system is required in order to supply nutrients to the cell fast enough and remove waste products quickly to prevent them building up to dangerous levels
What is diffusion?
Diffusion is the movement of molecules from a region of high concentration to a area of low concentration
What is diffusion affected by?
The rate of diffusion is affected by temperature, surface area and concentration gradient
