Cell Replication Flashcards
What is the cell theory?
- All living organisms are made of cells
- Cells are the basic unit of life
- All cells come from pre-existing cells
What are somatic cells?
Cells that aren’t gametes
What are the two types of cell division?
Mitosis - production of diploid somatic cells
Meiosis - production of haploid gametes
Why do cells replicate?
- Restore nucleus to cytoplasm ratio
- Growth and development
- Maintenance and repair
What is the cell cycle?
Life cycle of a cell involving growth, replication of DNA and division to produce two identical daughter cells
In the cell cycle, what is the main focus of the interphase stage?
The cell doubles its mass and duplicates its entire components
In the cell cycle, what is the main focus during mitosis and cytokinesis?
During mitosis, the nucleus divides.
During cytokinesis, the cytoplasm divides (marks two new cells)
What is mitosis?
Division of the nucleus into 2 genetically identical daughter nuclei
Function of mitosis
Growth, repair, maintenace
What are the phases of mitosis?
Interphase, prophase, metaphase, anaphase, telophase
What is a centromere?
Centromeres are the centre of the chromosomes (holds the chromatids together)
Process of Interphase
Duplication of cell insides e.g. organelles, nucleus, chromosomes etc.
Process of Prophase (in general)
- chromosomes condense
- nucleus disappears
- centrioles form spindle fibres and attach to the centromere of chromosomes
Process of early prophase
- Condensing of chromosomes (shorten and thicken, can be visible under the microscope)
- Centrosomes separate
- Nucleus dissolves
- Formation of the mitotic spindle
Process of late prophase
- nuclear membrane breaks down
- centrioles begin to form a network of fibres called spindle fibres (goes to the two poles of a cell)
- centromere of each individual chromosomes attaches to spindle fibres
Process of metaphase
- Chromosomes align in the middle of the cell
- Spindle fibres attach to centromeres of chromosomes
(Easiest stage to observe chromosomes)
Process of Anaphase
- Spindle fibres contract and the centromeres are pulled in the opposite direction
(Chromosomes split to chromatids) - Cell elongates
Process of telophase
- Nuclear membrane reforms around two sets of chromosomes
- Spindle fibre disappears
- Chromosomes become longer, thinner and uncondense
- Cytokinesis begins during telophase
Process of Cytokinesis
- Cytoplasm divides and separates into two daughter cells
How does cytokinesis occur in animal cells?
Cell membrane moves inwards and pinches the two daughter cells apart
How does cytokinesis occur in plant and fungi cells?
New membrane and cell wall forms between two daughter nuclei
What are some places mitosis occurs in humans?
Bone marrow, epithelia tissue e.g. skin, hair etc.
What is the apical meristem?
Usually the shoot/tip and the root tip (provides height growth)
What is the lateral meristem?
Occurs in the cambium of the shoot/trunk (provides secondary growth, width)
What are some places mitosis occurs in plants?
Occurs in the meristem of the plant (lateral and apical meristem)
What is meiosis?
Responsible for producing gametes (sperm and egg)
How many daughter cells does meiosis produce?
4 non-identical daughter cells
Note: All daughter cells are haploid