Y12 MW - Cell Division (Complete) Flashcards
How many chromosomes are found in a bacterial cell?
One - a circular piece of DNA
What type of cell division occurs in prokaryotic cells?
Binary fission
What is the process of binary fission?
The single, circular DNA molecule and any plasmids undergo DNA replication
Cytokinesis occurs where the parent cell divides into two daughter cells
Two daughter cells are therefore produced, each genetically identical
What are the different stages of the cell cycle?
G1, the S phase, G2 (altogether known as interphase) and mitosis
What are the three phases of interphase? Describe these
G1 - first growth phase where protein synthesis occurs and the number of organelles and cytoplasm increases
S phase - DNA replication
G2 - Second growth phase where the cytoskeleton of the cell breaks down and the spindle fibres begin to form
True or false? Interphase can be observed within a cell
False
What is mitosis?
The process of nuclear division where two genetically identical daughter cells are produced from one parent cell
What is mitosis required for?
The replacement of cells and repair of tissues
What are the stages of mitosis?
Prophase
Metaphase
Anaphase
Telophase
What must occur before mitosis?
Interphase
What occurs during prophase?
The chromosomes condense onto histones and so are now visible when stained
The nuclear membrane breaks down
What occurs during metaphase?
The chromosome line up at the equator of the cell
The spindle fibres reach the chromosomes and attach to the centromere so each sister chromatid is attached to a spindle fibre from an opposite pole
What occurs during anaphase?
The sister chromatids separate at the centromere and the centromere splits in two
The spindle fibres begin to shorten, pulling the sister chromatids to opposite poles of the cell
What occurs during telophase?
The spindle fibres break down
The nuclear envelope reforms around each set of chromosomes
What is the last stage of mitosis?
Cytokinesis where the cytoplasm and cell divides into two, forming two genetically identical daughter cells
How do cancers arise?
Uncontrolled mitosis
What is a tumour?
An irregular mass of cells
What is cancer?
Uncontrolled cell division which causes a malignant tumour
What is the difference between malignant and benign?
Malignant - can travel through the body and invade other healthy tissues
Benign - doesn’t spread around the body to other tissues
Name some risk factors for cancer
Obesity
Alcohol intake
Age
Genetics
Smoking
Processed food
UV light
What is metastasis?
When tumour cells invade other tissues, resulting in secondary cancers forming in the body
What does cancer treatment focus on?
Controlling cell division
Destroying tumour cells
How do viruses replicate?
The virus attaches to a cell using attachment proteins to bind to the complementary receptor proteins on the surface of the cell
The virus penetrates the cell membrane and injects its nucleic acid (RNA / DNA) into the cell
The viral nucleic acid undergoes semi-conservative replication using the host cell’s cellular machinery such as ribosomes and enzymes
The new viral nucleic acids are packaged into viral particles and are released when the host cell bursts
What is the difference between the structure of prokaryotic and eukaryotic DNA
Prokaryotes:
- Shorter DNA
- No histones
- Loop of DNA / RNA
- Circular chromosomes
Eukaryotes:
- Longer DNA
- Condensed into histones
- Linear chromosomes
How is the DNA of chloroplasts and mitochondria similar to that of prokaryotic cells?
They have 70S ribosomes
Circular loop of DNA (in the stroma of chloroplasts and the matrix of mitochondria)
