The Mitotic Cell Cycle

what are the different structures of a chromosomes

1) DNA 2) histones 3) telomeres 4) sister chromatids 5) centromeres

describe the structure of DNA in chromosomes

a chromosome is made from one very long condensed DNA molecule that contain coding base sequences, is associated with proteins

describe the structure of histones in chromosomes

is the main (globular) protein associated with chromosomes, are to organise and condense DNA to enable it to fit in the nucleus

describe the structure of telomeres in chromosomes

at end of each chromatid, capped with repetitive DNA, and prevent the DNA from damage

describe the structure of sister chromatids on chromosomes

after DNA replication in the S phase, chromosome consists of two identical sister chromatids, make up the double structure of the chromosome

describe the structure of centromeres when considering chromosomes

is the point where the two sister chromatids are attached, ensure they are pulled apart as spindle fibres attach here

list the factors that outline the importance of mitosis in production of genetically identical daughter cells

1) growth of multicellular organisms 2) replacement and repair of damaged cells 3) asexual reproduction 4) immune response

explain the factors for the importance of mitosis

1) identical daughter cells —> increases the cells in an organism 2) produces new cells with identical genetic information, ensuring function remains the same 3) produces genetically identical cells that enables restoration of normal tissue function 4) cloning of B and T lymphocytes requires mitosis —> need this to fight pathogens

what are the two main steps for the mitotic cell cycle

interphase —> mitotic phase (mitosis and cytokenisis)

what are the phases in interphase

G1, S phase, G2

what is the role of G1 phase in interphase

Is the first growth phase, replicates organelles and synthesises proteins needed for DNA replication

what is the role of S phase in interphase

DNA is replicated so two identical daughter cells are present

what is the role in G2 phase in interphase

continues cell growth, checks DNA for errors

what is the role of mitosis in the M phase

Mitosis separates the sister chromatids in the cell through PMAT ensuring each nucleus has an identical set of chromosomes

what is the role of cytokinesis in the M phase of cell cycle

cytokinesis divides the cytoplasm to form the cleavage furrow, this then produces two identical daughter cells

outline the order of steps in the mitotic phase

prophase, metaphase, anaphase, telophase

describe what happens at prophase

the nuclear envelope disappears, chromatin coils up to form chromosomes. Spindle fibres start to form and centrosomes move to opposite poles of cell

describe what happens at metaphase

the chromosomes line up at the equator and spindle fibres attach to the centromeres

describe what happens at anaphase

the sister chromatids are pulled apart and move to opposite poles of the cell due to shortening microtubules

describe what happens at telophase

nuclear envelope reforms around each set of chromosomes. Chromosomes uncoil to form chromatin, spindle fibres disappear.

what are the roles of telomeres

telomere = capped repeating DNA that is non-coding. Telomeres ensure important genetic information is not lost, allows the chromosome to efficiently crate genetically identical cells

what is the role of totipotent stem cells and what do they often appear as

totipotent stem cells often appear as a zygote, they are able to differentiate into embryonic cells and extra-embryonic cells

what is the role of pluripotent stem cells and what do they often appear as

often appear as blastocysts the inner cell mass and are able to differentiate into embryonic cells

what is the role of multipotent stem cells and what do they often appear as

often appear as inner mass cells that have become specialised for a specific function —> such as growth, cell replacement and repair

what is an oncogene

a mutated gene that can cause cancer

what is a proto-oncogene

a normal gene that regulated cell division

what can an oncogene lead to

oncogenes can lead to unregulated cell division that can cause cancer

what can uncontrolled cell division lead to and how

can lead to a tumour, mutated proto-oncogenes as well as damage to DNA or mutation when continuously divided results in large mass of abnormal cells

what is a benign tumour

a tumour that is mostly harmless and does not spread

what is a malignant tumour

a tumour that can pose harm and spread to rest of body