5: Mitotic Cell Cycle Flashcards
(20 cards)
Structure of a chromosome
-Two identical sister chromatids
-Joined at the centromere
-Telomeres at the end of the chromosomes
Importance of mitosis
- Growth of multicellular organisms
- Repair of tissues by cell replacement
- Replacement of dead cells
- Asexual reproduction
Define totipotent (2)
-Stem cells which can differentiate into any embryonic cells
-And extra embryonic cells
Where are adult stem cells found in the body
- Bone marrow
- Skin tissue
- Cardiac tissue/ Heart
- Brain/ nervous tissue
- Digestive system
Which enzyme is responsible for maintaining the length of telomeres
Telomerase
What happens in the G1 phase of the cell cycle
RNA, enzymes and proteins are produced;
Cell growth;
Replication of organelles;
Describe cytokinesis in a plant cell
A cell plate forms in the middle of the cell;
The cytoplasm is divided into two daughter cells
What is an oncogene
A mutated gene that causes cancer
Importance of controlling cell cycle length in mammals
Prevents tumor formation;
Enables some parts to grow faster/slower;
Limits occurrence of mutations in parts where the cell cycle is slower
Role of telomeres in chromosomes
Ensure all of the DNA is replicated;
So no genetic information is lost during mitosis
What is a stem cell?
An unspecialized cell which can divide by mitosis an unlimited number of times
What is a malignant tumor
A cancer causing tumor;
That spread from its original site through the blood steam/ lymph (metastasis);
Describe the stages in development of cancer
A mutation/ oncogenes arise due to carcinogens;
The mutated cell does not respond to signals and continues to divide by mitosis;
The immune system does not destroy the cells;
The tumor grows and is supplied with blood and lymph vessels;
The tumor cells break away and spread via the blood/ lymph to other parts of the body(metastasis);
Secondary cancers occur
Process of cytokinesis in animals
A contractile ring which is the cleavage furrow forms;
Which separates the cell into two daughter cells
Factors that affect the duration of a cell cycle in multicellular organisms
Cell type
Organism
Conditions
What happens to a chromosome between the beginning of telophase and the next round of mitosis
Chromosomes decodense;
Chromosomes is enclosed inside a new nuclear envelope;
DNA replication occurs (s phase);
New DNA wraps around histone proteins;
New DNA is checked for errors and any errors are repaired (G2 phase)
What occurs during metaphase?
Centrosomes reach opposite poles;
Chromosomes line up at the equator;
Spindle fibres attach to the centromeres
What occurs during prophase?
Chromosomes condense (supercoiling) and are visible;
Nucleolus breaks down;
Nuclear envelope breaks down into small vesicles;
Centrosomes move to opposite poles of the cell;
Spindle fibres emerge from the centrosomes
What occurs during anaphase?
The spindle fibres shorten;
Pulling chromatids apart by the centromere which divides into two;
To opposite poles
What occurs during telophase?
Nucleolus reforms;
Nuclear envelope reforms;
Chromosomes arrive at opposite poles and decondense;
Spindle fibres break down
