Topic 1a: Cell Biology: Cell Structure and Cell Division Flashcards
3, 4
Define specialised cell
A cell that is made to perform a specific function
Define differentiation
The process
by which a cell changes
to become specialised for its job
When does most differentiation occur?
As an organism develops
What boundaries do differentiated animal cells experience when compared to plant cells?
In most animal cells, the ability to differentiate is then lost after they become specialised
Lots of plant cells never loose this ability
Some animal cells can differentiate in mature animals; what are they mainly used for?
Repairing or replacing cells
Name 5 examples of specialises cells
- Sperm cells
- Nerve cells
- Muscle cells
- Root hair cells
- Phloem and xylem cells
State the purpose of a sperm cell
Reproduction: to get the male DNA to the female DNA
How is a sperm cell specialised for its function?
Long tail and streamlined head - helps it swim to the egg
Lots of mitochondria - provide the energy needed to locate an egg
Carries enzymes in its head - to digest through the egg membrane
State the purpose of a nerve cell
Rapid signalling: to carry electrical signals from one part of the body to another
How is a nerve cell specialised for its function?
Long - to cover more distance
Have branched connections at the end - larger surface area to connect to other cells and form a network throughout the body
State the purpose of a muscle cell
Quick contraction
How is a muscle cell specialised for its function?
Long - lots of space to contract
Contain lots of mitochondria - to transfer the energy needed for contraction
State the purpose of a root hair cell
Absorbing water and minerals
Where on a plant are root hair cells located?
The surface of plant roots
How are root hair cells adapted to their function?
Grow into long ‘hairs’ that stick out into the soil - giving the plant a big surface area for absorbing water and mineral ions
Have a large vacuole - allows for the storage of lots of water and mineral ions
Thin cell walls - easier to absorb water and mineral ions
How are phloem and xylem cells adapted to their function?
Long and joined at the end - to form tubes for transportation
Xylem are hollow & phloem have few sub cellular structures - so substances can flow through them
What is contained in the nucleus?
Genetic material needed to grow and develop
What form is genetic information stored in the nucleus?
As chromosomes
Why do organisms have pairs of chromosomes?
One from the ‘mother’ and one from the ‘father’
How many pairs of chromosomes should exist in each human cell?
23
How many chromosomes should exist in each human cell?
46
What are chromosomes made up of?
Long lengths of a molecule called DNA
What are the arms of the chromosomes made up of?
Coiled up DNA
What is a gene?
Short sections of DNA
What do genes control?
Our characteristics and development of characteristics e.g. hair colour and eye colour
Define the cell cycle
A stage of cell growth
and DNA replication
followed by a stage of cell division
Define mitosis
When a cell reproduces itself
by splitting to form two
identical offspring
What is mitosis used for in multicellular conditions?
Grow and develop
or replace cells
that have been damaged
Nucleus
Contains genetic material that controls activity of the cell
Cytoplasm
a gel-like substance where most of the chemical reactions happen. It contains enzymes (see p. 115) that control these chemical reactions.
