Unit 1 - Cell Biology Flashcards
What are micrometres?
1 mm = 1000 μm
How do you work out magnification?
Magnification = size of image / actual size (IAM triangle)
What are limitations of a light microscope?
Lower magnification,
What are the roles of cell structures?
Cytoplasm - where chemical reactions take place
Nucleus - controls cell’s activities and contains DNA
Cell Membrane - controls movement of substances in and out of the cell
Mitochondria - where energy is released via respiration
Ribosomes - where photosynthesis occurs
Chloroplasts - contains chlorophyll which absorbs light for photosynthesis
Cell wall - strengthens and supports the plant
Permanent vacuole - filled with sap to keep cell turgid
What is a specialised cell?
Cells which are designed to carry out a particular role via specific characteristics, such as red blood cells which have a biconcave shape to carry oxygen.
What is the difference between prokaryotic and eukaryotic cells?
Eukaryotic cells have a nucleus in which DNA is stored (such as animal and plant cells)
Prokaryotic cells have no nucleus and so their DNA is stored in rings called plasmids
What are the features of a prokaryotic (bacterial) cell?
-Much smaller - around 0.2 μm – 2.0 μm
-No chloroplasts, no mitochondria
-DNA is a single molecule, also found on rings called plasmids
-Cell division - binary fission
By what process do bacteria reproduce?
Binary fission, where the bacteria cell divides into two identical daughter cells, each with a copy of the parent’s genetic material
How do bacteria reproduce?
Bacteria can replicate approximately every 20 minutes. Depends on the availability of nutrients and conditions like temperature and pH, such as neutral or slightly acidic conditions.
How can we reproduce bacteria?
Colonies on agar plates - nutrient broth solution provides all nutrients for bacteria to grow, such as: carbs for energy and nitrogen for protein synthesis. The bacteria are spread onto agar plates to form individual colonies of specific bacterium.
What is aseptic technique?
Aseptic techniques ensure microorganisms being investigated do not escape or become contaminated, also preventing the growth of unwanted pathogens.
What are the examples of aseptic techniques?
-Flaming culture bottle necks to prevent contamination
-Using sterile loops when transferring cultures
-Washing hands thoroughly
Required practical - investigating effect of antiseptics/antibiotics on bacterial growth
-Sterilise petri dish to kill bacteria
-Pour the sterile agar plates
-Sterilise inoculating be heating in Bunsen flame to kill any bacteria present on the loop
-Dip loop into microorganism and spread out on agar plate using a spreader
-Replace the lid as soon as possible and secure with tape, store upside down to stop airborne bacteria contaminating the plate
-Do not fully seal lid, as this will stop oxygen reaching the bacterium to grow anaerobic bacteria
-Incubate at school temp of 25 degrees to stop harmful bacteria growing.
What are the processes in the cell cycle? (mitosis)
Mitosis is a process of cell duplication where one cell gives rise to two genetically identical daughter cells via the duplication and distribution of chromosomes.
-Prophase - the DNA in chromosomes condenses, the membrane around nucleus disappears
-Metaphase - chromosomes & copies line up in middle of cell
Anaphase - chromosomes & copies pulled to different ends of cell
Telophase - new membranes form around chromosomes at ends of cell
Cytokinesis - cell membrane pinches and divides into two daughter cells
What are stem cells?
Cells which have not undergone differentiation
Where are stem cells found?
Humans - embryonic stem cells are found in the early stages of development of the embryo
Adult stem cells remain in the bodies of adults, in places such as: brain, eyes, blood, heart etc
Plants have stem cells in the meristem
Some stem cells are still made in bone marrow, but can only specialise into blood cells
What is the difference between mitosis and meiosis?
Mitosis produces diploid (46 chromosomes) cells that are used for growth and repair
Meiosis produces haploid (23 chromosomes) cells that are used to create gametes
What is diffusion?
The movement of particles from an area of high concentration to an area of low concentration down the concentration gradient. It is passive as it requires no energy.
What is osmosis?
The movement of water particles from an area of high concentration to an area of lower concentration through a partially permeable membrane. Water moves in if the concentration is higher outside
What is active transport?
The movement of particles from an area of low concentration to an area of high concentration. It moves against the concentration gradient and so requires energy.
What are embryo clones used for?
Embryonic clones of a person are made to harvest cells from. These cells can be used to treat conditions without them being rejected by the patient’s body.
Why do we use cloning?
To preserve a species or produce crops with desired traits
