Biology : Cells and Control Flashcards
What do chromosomes contain?
Genetic Information
What are chromosomes?
Coiled up lengths of DNA molecules
How many copies of chromosomes do body cells usually have?
Two
If there are two copies of a chromosome, what does that make the cells?
Diploid cells
Are the two cells created by mitosis identical or not?
Identical
Do the nucleus of each of the two cells contain the same number of chromosomes or not?
They do
What is the process in which body cells divide to produce new cells called?
The Cell Cycle
What is the stage of the Cell Cycle called when the cell actually divides?
Mitosis
What do multicellular organisms use mitosis for?
To grow or replace (damaged) cells
What do some other organisms use mitosis for?
Asexual reproduction
What is the first stage of the Cell Cycle?
Interphase
What happens in Interphase?
The cell grows and increases the number of subcellular structures (mitochondria, ribosomes). After which, it duplicates the DNA, to form a ‘x’-shaped chromosome, where each arm of the chromosome is exactly the same
What is the second stage of the Cell Cycle?
Prophase
What happens in Prophase?
Chromosomes condense, getting shorter and fatter
Membrane around nucleus breaks down, chromosomes lie free in cytoplasm
What is the third stage in the Cell Cycle?
Metaphase
What happens in Metaphase?
Chromosomes line up in the centre of the cell
What is the fourth stage of the Cell Cycle?
Anaphase
What happens in Anaphase?
Spindle fibres pull the chromosomes apart
Chromatids are pulled to opposite ends of the cell
What is the fifth stage of the Cell Cycle?
Telophase
What happens in Telophase?
Membranes form around each set of chromosome
These become the nuclei of the new cell
The nucleus has divided
When does Cytokinesis occur?
Before Telophase ends
What happen in Cytokinesis?
The cytoplasm and cell membrane divide to form two separate cells
What is produced at the end of mitosis?
Two new daughter cells
What are the two genetically identical daughter cells also genetically identical to?
The parent cell
How can you calculate the number of cells produced after multiple divisions?
Use the equation:
Number of cells = 2^n
With (n) being the number of division by mitosis
What is growth?
An increase in size or mass
What is cell differentiation?
The process by which a cell changes to become specialised for its job
Is having specialised cells more effective for multicellular organisms?
Yes, they work more efficiently
What is cell elongation?
A plant cell expands, making the cell bigger and so the plant grows
Does all growth in animals happen by mitosis?
Yes
When is there a faster rate of cell division?
When animals are young
What is most cell division for when animals stop growing?
To repair damaged cells
What is the main way for plants to grow in height?
Cell elongation
Where does cell division usually only happen in plants?
Tips of roots and shoots, in areas called meristems
Do plants grow continuously?
Yes, old trees still grow new branches