OCR F211 Cell Division, Cell Diversity and Cellular Organisation

HideShow resource information
  • Created by: Bethany.
  • Created on: 29-04-16 17:50
Preview of OCR F211 Cell Division, Cell Diversity and Cellular Organisation

First 333 words of the document:

Module 1: Cells
1.1.3 Cell Division, Cell Diversity and Cellular Organisation
(a) state that mitosis occupies only a small percentage of the cell cycle and that the remaining percentage
includes the copying and checking of genetic information
M = Mitosis The nucleus divides and
chromosomes separate
occupies only a small
percentage of the cell cycle
Cytokinesis The splitting of two cells takes
place after mitosis
G 1 = Growth
Biosynthesis proteins are made
1 and organelles replicate
S = Synthesis Synthesis of DNA DNA
replication, last structure to be
G2 = Growth
Growth cell growth until it
2 becomes large enough for
division/preparation for mitosis
Interphase G1
, S and G2
where DNA and
organelles are copied and
checked for any errors that may
have occurred during copying
occupies most of the cell cycle
(b) describe, with the aid of diagrams and photographs , the main stages of mitosis (behaviour of the
chromosomes, nuclear envelope, cell membrane and centrioles)
Stage Description
Interphase The cell grows and prepares for mitosis, checking for any errors
The DNA is replicated
Prophase The chromosomes condense , getting shorter and thicker
The nuclear envelope breaks down and disappears and the chromosomes lie free in
the cytoplasm
Tiny bundles of proteins called centrioles divides into two and move to opposite poles
to form a network of protein fibres called the spindle
Metaphase The chromosomes move to the central region of the spindle (the equator) and each
becomes attached to a spindle thread by its centromere
Anaphase The spindle fibres shorten, pulling the sister chromatids further and further away from
each other towards the poles
Telophase The chromatids reach the opposite poles and they uncoil and become long and thin
The spindle breaks down and disappears
The nuclear envelope forms around each set

Other pages in this set

Page 2

Preview of page 2

Page 3

Preview of page 3

Here's a taster:

Module 1: Cells
Diploid or Haploid? Diploid cells have 2 copies of each Haploid cells have one set of
chromosome in their nuclei chromosomes
Number of Remains the same Reduced by half
chromosomes in
daughter cell
Genetically Genetically identical Not genetically identical
One chromosome in each pair comes from each parent and theyare the same size and have the same genes,
although they could have different versions of those genes (called alleles) these are homologous pairs
(d) explain the significance of mitosis for growth,…read more

Page 4

Preview of page 4

Here's a taster:

Module 1: Cells
During cell division by meiosis, homologous chromosomes pair up and one member of each pair goes into each
daughter cell . Most eukaryotes have pairs of homologous chromosomes because one is inherited from each
parent . They carry the same genes but may carry different alleles of each.
(g) define the term stem cell
Only SUM cells are stem cells in adult organisms, for example:
in bone marrow of human adults
in meristems (e.g.…read more

Page 5

Preview of page 5

Page 6

Preview of page 6

Here's a taster:

Module 1: Cells
Plant Palisade Contain many chloroplasts (containing chlorophyll) so they can absorb lots of
Cells light for photosynthesis
Cells Thin so gases can easily diffuse
Root Hair Long and thin providing a large surface area for the absorption of water and
Cells mineral ions
Lots of mitochondria to provide energy needed for active transport
Guard Cells Contain chloroplast and cellulose
When the cells become turgid , the outer wall stretches causing the guard
cells to bulge and form a pore (stomata ) between…read more

Page 7

Preview of page 7

Here's a taster:

Module 1: Cells
(l) discuss the importance of cooperation between cells, tissues, organs and organ systems
Multicellular organisms work efficiently because they have different cells specialised for different functions. It's
advantageous because each different cell type can carry out its specialised function more effectively than an
unspecialised cell could. Specialised cells can't do everything on their own . Each cell type depends on other cells
for the functions it can't carry out.…read more


No comments have yet been made

Similar Biology resources:

See all Biology resources »See all resources »