1.2 Cells Divison Flashcards
What are chromosomes made up of?
Chromosomes consists of DNA molecules combined with proteins. They contain genes which provide the instructions for protein sythesis
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 3 main stages of the cell cycle?
-Replication of DNA and synthesis of organelles
-Mitosis
-Division of cell
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 cell cycle
Longest stage- cells grow and increase in mass, replicate DNA and synthesise more organelles
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 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 eg. 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 patients immune system, so can be used to treat certain medical conditions