Cell Biology (B)(p1/2) Flashcards
What are the 3 stages of cell cycle
Growth
DNA replication and mitosis
-division (cytokinesis
What happens during the growth stage of a cell?
There is an increased number of sub cellular structures (mitochondria )
How many chromosomes do humans have?
46 (2 pairs of 23 from mom and dad)
How does the cell prepare for division?(mitosis/ DNA replication)
DNA is coiled up into chromosomes
The cell duplicates each chromosome (attaching to the original cell) forming an X shape
Then all chromosomes line up along cell centre. The fibres from edge of the cell attach to the half of the chromosomes.
Forming cell fibres
that pull arms of chromosomes(half) opposite sides of cell. Called poles.
What is cytokinesis?
Cell membrane and cytoplasm pull apart forming 2 daughter cells. Having the same DNA.being identical
What are stem cells and why are they important?
Cells divided by mitosis which differentiate into specialised cells
What are the stem cells in plants, adults and baby’s?
-baby[embryonic Stem cells] differentiate into any cell
-adult[adult stem cells] in bone marrow, differentiate into types of blood cells
-plant: found in meristems[ differentiate into all cells needed for plant. Lasting for life.
What are specialised cells
•have specific role in body, containing specific shape and structure. So have specific amounts of different organelles
Why is a sperm cell specialised? (3fts)
Flagellum: help cell swim through uterus & Fallopian tube to reach egg
Mitochondria: provide energy for cell
Digestive enzymes: break hole into egg
What is differentiation?
Process cell changes to become specialised
How can stem cells be used to treat disease?(4stps)
(Stem cells replace fault cells with properly working cells)
1.extract embryonic cells from early embryos
2. Laboratory growth
3.stimulate into any cell
4. Give to patient to replace
What are the risks of stem cell therapy?
1-embryonic stem cells are only cell to differentiate into any cell. Have limited supply and ethical issues
2- different genomes, destroying foreign cells, rejecting the cells.(can use medication to suppress, but not reliable.
3-transmit virus and chase tumours
Why do people think we should not use stem cells?
-embryonic stem cells gave potential for human life(band in country’s)[embryo RIGHTS]
-although are from fertility clinics , unwanted.
What is diffusion?
Diffusion is the net movement of particles to and area of higher concentration to an area of lower concentration
Through a partially permeable membrane to allow smaller molecules through.
NO ENERGY REQUIRED (passive process)
What factors affect diffusion?(3)
-difference in concentration in 2 places (concentration gradient)larger= higher diffusion
-temperature. Higher moves faster and quicker.
-surface area: larger area =higher diffusion
What is osmosis
The net movement of water molecules through a partir lay permeable membrane from a regien of higher water concentration to lower water concentration.
(Ratio of water:solutes determines concentration)
What are solutes?
Dissolved sugars/salt in water.
What is active transport?
The movement of molecules across a cell membrane from a region of lower concentration to region of higher concentration
( requiring energy from cellular respiration)
Why does a plant need to use active transport?
There are higher concentration minerals in root hair cell than outside. So as they need minerals to survive. Will have to use energy for active transport
What is surface area to volume ratio?
How big the surface area is compared to volume
(Bigger organism, surface area:volume decreases)
Higher SA:V are bacteria cells(rely on diffusion)
Low SA:V are humans( relay on specialised exchange surface)
What are specialize exchange systems
Used in most multicellular organisms due to low surface area: volume
What is a passive process?
A process that doesn’t require energy
What is a hypotonic solution?
A solution with low solute concentration and high water concentration
What happens when a potato is in a concentrated sugar / salty solution?
Water will leave the cell. So the mass will decrease
