Cell Division Flashcards
What are chromosomes made up of?
Chromosomes consist of DNA molecules combined with proteins. They contain genes which provide the instructions for protein synthesis
What is a gene?
A section of DNA which codes for a protein
How many chromosomes are found in the nucleus of human body cells?
46
How many chromosomes are found in the nucleus of gametes?
23
How are chromosomes arranged in the nucleus of a body cell?
Arranged in pairs: 46 Chromosomes form 23 pairs
What are the main three stages of the cell cycle
- Replication of DNA and synthesis of organelles
- Mitosis
- Division
Why is mitosis important?
- Produces identical cells which all have the same genetic information
- Produces additional cells for growth and repair
Describe the first stage of the cell cycle
Longest Stage - Cells grow and increase in mass, replicate DNA and synthesise more organelles (e.g. mitochondria, ribosomes)
Describe the second stage of the cell cycle
Each chromosome in a pair is pulled to opposite poles of the cell, then the nucleus divides.
Describe the third stage of the cell cycle
The cytoplasm and cell membrane divide, two identical daughter cells are produced
What is a stem cell?
An unspecialised cell which is capable of differentiating into other cell types and of self-renewal
What is the function of stem cells in embryos?
Embryonic stem cells can replicate themselves and differentiate into many other types of cells.
Embryonic stem cells may be able to treat conditions such as paralysis and diabetes by dividing to replace damaged cells
What is the function of stem cells in adult bone marrow?
Adult stem cells can differentiate into several cell types to replace dead or damaged tissues. For example, bone marrow stem cells can form many different types of blood cell
What is the function of stem cells in plant meristems?
Meristem stem cells retain the ability to differentiate into any type of plant cell throughout their lifespan - they can differentiate into any cell which is required by the plant.
What is therapeutic cloning?
A cloning method where an embryo is produced with the same genetic makeup as the patient.
The stem cells which originate from the embryo will not be rejected by the patient’s immune system, so can be used to treat certain medical conditions
What are the advantages of cloning plants using meristem stem cells?
- Can prevent rare plants from becoming extinct
- Can produce large numbers of plant with a favourable characteristic
- Can produce identical plants for research
What is asexual reproduction?
Producing new organisms from one parent only. These organisms are genetically identical to the parent
What is a cancer Cell?
A cell that divides uncontrollably
What is the cell cycle?
A sequence of growth and division that happens in cells. It includes interphase and mitosis, and leads to the production of two daughter cells that are identical to the parent cell
What is a clone?
Offspring from asexual reproduction. All the cells in a clone are genetically identical to each other and to the parent’s cells
What is a daughter cell?
New cell produced by cell division
What is a diploid?
A cell with two sets of chromosomes
What is DNA replication
The copying of the DNA within a cell.
What is a haploid?
A cell with one set of chromosomes
What is mitosis
The process of cell dividing to produce two daughter cells that are genetically identical to the parent.
Multicellular
An organism that is made of many cells.
What is a tumour?
Lump formed of cancer cells.
What is differentiation?
When a group of similar things, such as cells, become different in form from each other
What is growth?
A permanent increase in the number or size of cells in an organism
Differentiate
To change into different types, for example when meristem cells differentiate into specialised cells such as xylem or root hair cells
What is a root hair cell?
Cell found on the surface of plant roots that has a large surface area to absorb water and dissolved mineral salts quickly from the soil
What is a xylem cell?
Cells that join with other xylem cells to form long, thick-walled vessels after they die. The vessels after they die. The vessels carry water and dissolved mineral salts through the plant
What is cancer?
A disease caused by the uncontrolled division of stem cells in a part of the body?
What is a stem cell?
Unspecialised cell that continues to divide by mitosis to produce more stem cells and other cells that differentiate into specialised cells
