Mitosis, Exchange Surfaces and Lungs Flashcards
What is Mitosis?
type of cell division resulting in genetically identical diploid cells.
What is the purpose of mitosis?
repair, growth and development of tissues in multicellular organisms
asexual reproduction
What type of reproduction is mitosis, and what is its version in bacteria?
Asexual reproduction, binary fission
What is the order of stages in cell division?
G1, S, G2, Mitosis, Cytokinesis, G0
What does the G stand for in cell division?
Growth
What does the S stand for in cell division?
Synthesis
What happens in the G1 phase of cell division?
Subcellular structures (eg mitochondria) duplicate
What happens in the S phase of cell division?
DNA replicates. now two copies of each chromosone
What happens in the G2 phase of cell division?
DNA is checked for errors during replication. Enzymes are used to fix the mistakes.
What happens in mitosis?
The chromosones move to opposite poles of the cell and two nuclei form.
What happens in the G0 phase of cell division?
Temporary cell resting. Some cells will never divide again, eg, nerve cells
How many chromosomes and pairs in a human adult cell?
46 chromosomes
23 pairs
How many chromosomes and pairs in a sperm or egg cell?
23
What happens in the prophase?
1) Chromosomes formed of 2 sister chromatiPs
2) nuclear membrane disaPPears
3) SPindle fiPres form
What happens in the metaphase?
1) ChroMosoMes line up aloMg the equator
2) SpiMdle fibres attach to the ChroMosoMes
What happens in the anaphase?
1) Sister chromatids pulled apart towards poles
What happens in the telophase?
1)Nuclear membrane reform, creaTing Two nuclei
What happens in cytokinesis?
1)cytoplasm+cell membrane divide, leaving two diploid daughter cells
In which stage of cell division does the cytoplasm and cell membrane divide?
Cytokinesis
In which stage of cell division does the nuclear membrane reform?
Telophase
In which stage of cell division do the chromatids line up along the equator?
Metaphase
In which stage of cell division do the spindle fibres form?
prophase
In which stage of cell division do the nuclear membranes disappear?
prophase
In which stage of cell division are the sister chromatids pulled towards the poles?
anaphase
Where do the spindle fibres attach to the chromosomes?
At the centromere
What are the spindle fibres made of?
Centriole
What does diploid mean?
Two copies of a chromosome
What are the disadvantages of mitosis?
Can cause cancer if g2 fails, not all cells can
What is the equation you need to do to work out whether simple diffusion is enough for an organism to respirate?
Surface area to volume ratio
Do large multicellular organisms have a small or large SA:V?
Small
Do small single cell organisms have a small or large SA:V?
Large
Why do large organisms require an exchange surface?
there’ll be layers of cells between the center and environment- products of respiration will be used up before they reach the surface
What are the features of an exchange surface? (4)
- large SA increases exchange site
- Thin membrane decreases diffusion distance
-a way to transport substances to/from exchange site
-steep conc gradient
How does inhalation take place?
- diaphragm contracts and flattens/moves down
- intercostal muscles contract
- ribs move in and out
- chest volume increases
- pressure decreases, air rushes in
How does exhalation take place?
diaphragm relaxes and moves up
- intercostal muscles relax
- ribs move down and in
- volume inside chest decreases
- air rushes out
How are small intestines adapted to be a good exchange surface?
- good blood supply
- one cell thick wall
- large SA- villi/microvilli
How are lungs adapted to be a good exchange surface?
- alveoli wall is very thin
- capillaries surrounding alveoli ensuring a good blood supply as oxygen is constantly moved round away from the lungs maintaining a steep concentration gradient
- well ventilated
- surfaces
How are fish gills adapted to be a good exchange surface?
- Good blood supply assists with quick absorption
- gill filaments have large SA
- thin walls for short diffusion distance
How are root hair cells adapted to be a good exchange surface?
-projections increase SA
-constant water flow
-thin walls for short diffusion distance
How are leaves adapted to be a good exchange surface?
- stomata- small holes for movement of gases
- flattened shape, large SA
- thin walls for short diffusion distance
What do plant leaves exchange
Co2 and oxygen
What do root hair cells exchange?
Water and mineral ions
What type of blood vessel is found in villi?
Capillaries
What type of blood vessel surrounds alveoli?
Capillaries
What is special about the way the intercostal muscles interact?
They act antagonistically.
Which intercostal muscle is stronger?
External
What links active transport and diffusion?
transport of solutes
