Flashcards in Cell Structure Deck (50):
Where protein synthesis occurs
Where most of the energy is released in respiration
Controls the passage of substances that come in & out of the cell
Controls activities of the cell
Most chemical reactions take place here (controlled by enzymes inside cells)
Filled with cell sap and when full supports the cell
absorbs light for photosynthesis
Cellulose cell wall?
Strengthens the cell
1mm = nm?
How long are eukaryotic cells?
How long are red blood cells?
What are prokaryotic cells?
Unicellular with no nucleus and much smaller than eukaryotic cells e.g bacteria & blue green algae
How long are bacterial cells?
Eukaryotic cells are about 10x bigger
Small whip like tail for propulsion
Possess genes which may aid the survival of bacteria
genetic info for replication of the cell
Cell surface membrane?
controls exit & entry of chemicals
Protection and helps bacteria to adhere to each other
Protects against damage and osmotic lysis
magnification (m) = size of image(I) / actual size of specimen
Objective lens x eyepiece lens
What are stem cells?
Differentiate into many cell types
Stem cells in animals?
Embryonic stem cells
Can differentiate into any cell in the body
Umbilical chord found
Adult stem cells?
Found in the bone marrow
Divide to repair
Replace damaged tissue
Stem cells in plants?
Non specialised stem cells are found in the meristems of plants
Found at tips of roots & shoots & in between the xylem & the phloem tissues
Can divide over and over to produce non specialised stem cells
Some continue to divide making the plant talked and wider
Can develope into any type of specialised plant cell and go on to form phloem , xylem, leaves and flowers
Pattern of growth?
Plants - often grow continuously
Animals- grow to a maximum size
How growth hAppens?
Plants-by cell enlargement
Animals- increasing no. Of cells
Where cell division happens?
Animals-in most tissues
Plants- many cells can differentiate
Animals- most cells lose ability to differentiate at an early stage
Stem cells in medical research?
-diseases can be treated
-embryo will die
-lack of research
-unsure of long term side affects
-body could reject if not self tissue
-difficult & long procedure
-donation requires license
What is mitosis?
Cell division in eukaryotic cells, they divide to produce two new identical copies
What are chromosomes?
Contain genetic info
Change in your genetic makeup
What are cancer cells?
Arise due to mutations in genes that control cell growth (mitosis) this leads to uncontrolled cell growth and results in a tumor
What is diffusion?
The random movement of particles from an area of high concentration to an area of low concentration i.e down a concentration gradient. Continues until the particles are at an even concentration
Where does diffusion occur?
Gas exchange in lungs
Gas exchange in leaf
Materials across capillaries
Substances across placenta
Factors affecting the rate of diffusion?
Temp- increase in temp means more kinetic energy for particles, more quickly so diffusion quicker
SA-bigger sa so more molecules can be diffused
Thickness of gradient pathway- the thinner the diffusion surface the faster the molecules will diffuse
Concentration gradient- steep only one side moves, shallow both sides move
What is osmosis?
The diffusion of water from a dilute to a more concentrated solution through a partially permeable membrane that allows the passage of water molecules
Osmosis in animal cells?
When RBC is put in dilute, water will enter by osmosis, RBC fills up, swell & burst (lysis)
When RBC is put in concentrated solution, water will leave by osmosis, RBC will shrivel (crenation)
Osmosis in plant cells?
The cell wall prevents from bursting (lysis)
Placed in more concentrated, water will leave cell by osmosis, cell membrane pulls away from the cell wall & plant is plasmalysed.
Placed in dilute e.g sugar, water will enter by osmosis, will fill up but won't burst, cell wall will stretch, plant is turgid
Swell = turgid
Shrivel = plasmalysed
What is active transport?
Cells may need to absorb substances that are in short supply. Transport Substances across a partially permeable membrane against the concentration gradient low to high using a carrier protein and energy. This happens from respiration.
What happens in active transport?
Molecules bind to carrier protein & energy from respiratiOn allows the molecule to cross the membrane
Active transport in living systems?
Glucose can be reabsorbed into the kidney tubules.
Obtain mineral ions through root hair cells
Na+ & K+ actively transported in neurons(nerve cells)
What do cells involved in active transport contain?
Lots of mitochondria BC lots of energy is needed to cross membrane