Cell Division and Cellular Organsiation Flashcards
What does the cell cycle consist of?
Interphase, mitosis and cytokineses
What happens during interphase?
It is split up into 3 phases
G1: cell checks chemical needed for replication are present
S: cell replicates its ready ready for mitosis
G2: The cell checks whether all the DNA has been replicated without damage
What is mitosis?
This is cell replication, creating a genetically identical cell
In mitosis state the stages and what happens in each stage
Prophase: Centrioles move to opposite ends of the cell, forming a network of spindle fibers
Metaphase: the chromosomes line up along the middle of the cell and become attached to the spindle by their centromere
Anaphase: sister chromatids move to opposite ends of the cell
Telophase: The chromatids reach the opposite poles and the nucleus envelope forms
What is cytokinesis?
The cytoplasm divides
How many chromosomes do a haploid and diploid cell have
Haploid: 23
Diploid: 46
What is meiosis?
This the production of gametes
In meiosis state the stages and what happens in each stage
Prophase 1: Chromosomes condense, get shorter and fatter
Metaphase 1: pairs line ip across the centre of the cell and attach to spindle fibres
Anasphase 1: Spindles contract, pulling the pairs apart (one goes to each end)
Telophase 1:
A nuclear envelope forms around each chromosome
Meiosis 2: (only difference is half number of chromosomes)
(anaphase 2 sister chromatids are separated)
Why is genetic variation needed in individuals?
This causes evolution individuals become immune to diseases and surviving against harsh environmental conditions.
What is cross over of chromatids and its effect?
Cromatids cross over meaning now they have a new combination of alleles
This causes genetic variation
What is a stem cell?
This is an unspecilied cell, it can develop into different types of cells
What is differentiation?
This when stem cells become new cells, then become specialized.
Stem cells are also able to divide to produce more undifferentiated stem cellls
What is a totipotent stem cell?
Found in a fertilised cell.
Can differentiate into any type of cell
What is a pluripotent stem cell?
Present in early embroys
They can form all tissues but not whole organsims
What is a multipotent stem cell?
Found in bone morrow
These stem cells can only form a range of cells within a type of tissue
How are erthrocytes adapted to fit there function?
They have a large SA for gas exchange (bicocave disk)
No nucleus to provide more room
How are Netrophils adapted to fit there function?
They have a flexible shape which allows them to engulf foreign particles
How are Epithelial adapted to fit there function?
This covers the surface of organs, they contain cilia which wafts the substances
How are sperm cells adapted to fit there function?
They have a flagellum so they can swim. They have lots of mitochondria to provide energy to swim.
How are palisade mesophyll cell adapted to fit there function?
This is found in most leaves. They contain many chloroplast for photosynthesis. They are also one cell thick do carbon dioxide can diffuse easily.
How are root hair cell adapted to fit there function?
They have a large surface area and a thin cell wall. The cytoplasm contains extra mitochondria to provide the energy needed for active transport
How are guard cells adapted to fit there function?
These are found in between the stomata. When guard cells take up water they become turgid resulting in the stomata opening
What is a tissue?
A group of similar cells that carry out a function
What is an organ?
A group of similar tissues that carry out a function
