8.1 Mitosis & Cell Division Flashcards
Nucleosome:
DNA wrapped around histones
Nucleic acid:
Chain of nucleotides
Cells need to divide for:
Growth
Tissue repair
When a cell divides it is important that the daughter cells receive…
Exactly the same genetic information as the parent cell
Cells divide to give exact copies of themselves by a process called…
Mitosis
Division of somatic cells produces…
Daughter cells
DNA is organised into…
Chromosomes
A cell that is not dividing is said to be in…
Interphase
Complex chromatin is…
Long threads of DNA wound around histones (protein molecules)
DNA replicates during…
Interphase (cannot see anything happening in the cell at this stage)
Chromosome is made up of…
Two chromatids held together by a centromere
Chromosomes consist of two chromatids as the DNA
Replicates during interphase - one of the chromatids is the exact same copy of the one joined to it
Uncoiled DNA is called…
Chromatin (between cell divisions)
Coiling happens during…
Cell division
Coiling is when…
DNA wraps tightly around proteins called histones
Chromosome consist of two..
Identical halves (chromatids) connected together by a centromere 23 pairs one from mother other from father
Chromatid is…
Half of one chromosome
Contains one complete set of info
Copies itself to make the other chromatid
2 chromatids = 1 chromosome
Sister chromatids (identical) formed prior to mitosis - DNA replication (S)
Human diploid (2n) has…
46 chromosomes
23 identical pairs - homologous chromosomes (carry the same traits)
Mitosis - first you duplicate DNA: why?
Have 2 pairs of 23 chromosomes
If cell splits, you will only have 1 pair
Duplicate DNA - if cell splits - still have 2 pairs
Importance of mitosis for growth?
Sperm and ovum fuse together = Zygote
Cell is diploid (46chromosomes - one set from each parent)
Zygote then divides by mitosis so that ALL the cells in the new organism have exactly the same information
So all the new cells contain exactly the same alleles
Importance of mitosis for repair:
If cells die or are damaged new cells need to be produced
It is important that the new are genetically identical as the cells they are replacing
Importance of mitosis for asexual reproduction:
Only requires one parent
All the offspring produced are identical to the parent
Can be an advantage when the environmental conditions are not changing
Enables an organism to produce many offspring very quickly
Examples of vegetative propagation are growing new plants from bulbs, tubers or cuttings
