SB2: Cells and Control Flashcards
What are the two types of cell division?
Mitosis and meiosis
How many pairs of chromosomes are there inside a nuclei?
23 pairs
Describe the two phases in the cell cycle.
Interphase: cell makes extra sub-cellular parts. DNA replication occurs, to make copies of the chromosomes, but they stay attached to each other forming an x shape.
Mitosis: cell splits to form 2 daughter cells, both identical to the parent cell. The cells are genetically identical.
When do cells divide?
- When an organism grows
- When an organism is damaged and needs new cells to repair itself
- For organisms that reproduce asexually
What are the stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis
What occurs in prophase?
- nucleus breaks down
- spindle fibres appear
What occurs in metaphase?
Chromosomes are their copies line up on the spindle fibres in the middle of the cell
What occurs in anaphase?
The chromosome copies are separated and moved to either end of the cell on the spindle fibres
What occurs in telophase?
A membrane forms around each set of chromosomes to form a nuclei
What occurs in cytokinesis?
- cell surface membrane forms to separate the 2 cells.
- cell walls form in plants
What are cancer cells?
Cells that divide uncontrollably
What are tumours?
A growth produced by a group of cancerous cells
Define growth
- increase in size as a result of increase in number/size of cells
- long-lasting permanent change
How is the growth of babies recorded?
Measuring:
- mass
- length
- head circumference
What are percentile growth charts?
a chart used to compare the growth of a baby to the growth of other babies
What are specialised cells and what process must they go through to become specialised?
Cells that have adaptations to carry out specific tasks or functions. They must go through differentiation to become specialised
What are the adaptations of a red blood cell?
- biconcave disk shape (increases surface area)
- no nucleus (increases surface area)
- protein called haemoglobin binds to oxygen to carry it easier
What are the adaptations of a fat cell?
- expands to store more fat/ shrinks when it loses it
- not a lot of mitochondria - no need for lots of energy
- can form a layer of fatty tissue around some organs for protection and energy
What are the adaptations of a muscle cell?
- Have proteins that allow the muscle to contract and relax for movement by sliding over each other
- lots of mitochondria
- lots of ribosomes to produce proteins
What are meristems and where are they located?
A group of cells near the end of each root and shoot that allows plants to continue growing ( plant stem cell) for the rest of their lives
What is cell elongation?
The process through which the plant continues to grow in length. Animals do not have this process
What are the adaptations of a root hair cell?
- a large surface area so they can absorb lots of water through osmosis
- thin cell walls so water can easily get in through the roots
- lots of mitochondria
What are the adaptations of a xylem cell?
- hollow
- line up next to each other forming a long hollow tube to carry water and mineral ions from roots and leaves
- thick walls to resist water pressure
- cells empty so no processes occurring which means water only travels upwards
What are the adaptations of a palisade cell?
- only found in leaves
- lots of chloroplasts to trap energy for photosynthesis
- can move to absorb as much light as possible
What are stem cells?
Cells that have not undergone differentiation
What is the difference between embryonic and adult stem cells?
- embryonic: before the baby is born, cells can differentiate into any type of specialised cell
- adults: can only differentiate into the type of specialised cell that is in the tissue around them