Specialisation of cells, organisation of living things and mitosis Flashcards
Where in a cell is the genetic information?
Nucleus
Put these in size order: chromosome, gene, cell, nucleus
Gene 🡪 chromosome 🡪 nucleus 🡪 cell
What are genes?
Short section of DNA that control characteristics
What are chromosomes?
A long section of DNA made up of many genes
How many chromosomes do humans have?
46 (23 pairs)
What is mitosis?
Mitosis is when a cell reproduces itself by splitting to form two identical offspring.
Why do multicellular organisms use mitosis?
To grow and develop or to replace cells that have been damaged.
What TWO things do cells have to do before they divide by mitosis to produce identical offspring?
The cell grows and increases the number of organelles (eg. Mitochondria and ribosomes). It then duplicates its DNA.
What THREE things happen during mitosis?
The chromosomes line up at the centre of the cell and the two arms of each chromosome are pulled to opposite ends of the cell. Membranes form around each set of chromosomes. These form the new nuclei. The cytoplasm AND cell membrane divide.
How many daughter cells are formed during mitosis?
2
How many cell divisions occur during mitosis?
1
How do the daughter cells compare to the parent cell?
They are identical
Why do cells duplicate their DNA before mitosis?
Otherwise the daughter cell would only have half the DNA of the parent cell.
What is the division of prokaryotic cells called?
Binary fission
What is cell differentiation?
The process by which a cell changes to become specialised for its job.
What are the cells that can differentiate called?
Stem cells
Give FOUR ways sperm are specialised for their function
Streamlined to swim to the egg. Long tail to swim to the egg. Lot of mitochondria to release energy for swimming. Enzymes in the head to break into the egg.
Give TWO ways nerve cells are specialised for their function
Very long to travel around the body. Branched connections at the end to connect to other nerve cells, forming a network.
Give TWO ways muscle cells are specialised for their function
Long, so have space to contract. Lots of mitochondria to release energy for contraction.
Give TWO ways root hair cells are specialised for their function
Long hair like structure has large surface area for absorbing water and mineral ions from the soil. Thin cell wall for short diffusion distance.
Give THREE ways xylem and phloem cells are specialised for their function
They form tubes to transport substances around the plant. Xylem are hollow in the centre so water can flow. Phloem have few organelles so substances can flow.
What is a tissue?
A group of similar cells that work together to perform a particular function.
What is an organ?
A group of different tissues that work together to perform a particular function.
What is an organ system?
A group of organs working together to perform a certain function.
