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Wednesday 29 March 2017

Reproduction

Asexual reproduction is a type of reproduction by which offspring occurs from a single organism, and inherit the genes of that parent only, it does not involve the fusion of gametes, and almost never changes the number of chromosomes.

Asexual reproduction requires only one parent. Since there is only one parent, there is no exchanging of genetic information, and the offspring are clones of the parent. Asexual reproduction in plants can occur in a variety of forms, including budding, vegetative propagation, and fragmentation.

Different types of asexual reproduction in animals and plants are
  • Stems. In some species, stems arch over and take root at their tips, forming new plants. 
  • Leaves. This photo shows the leaves of the common ornamental plant Bryophyllum.
  • Roots. 
  • Plant Propagation. 
  • Apomixis. 
  • Budding. 
  • Fragmentation. 

1. Rapid Populating
Asexual reproduction gives the ability to produce large quantities of of offspring. This helps to fill up niche’s quickly and prevent intruders and competition from invading.
2. No Mates Required
Finding a mate can be very difficult for organisms that are in desolate environments, like the deep ocean. Asexual reproduction takes the need to find a mate away, allowing these organisms to multiply.
3. In Case of Emergency
In terrible situations, plants and organisms can keep themselves alive and produce others to help them without the help of a mate, or other reproductive source. Plants are a great example of this. If no pollinator is available to pollinate, then they can clone by asexual reproduction.
4. No True Investment
Asexual reproducers do not have to carry their offspring for a long amount of time and produce more than one at a time. This makes it a quick and inexpensive process for them in the terms of time.



Thursday 2 March 2017

Science

Why do cells reproduce:  Growth - increase in number of cells
                                         Maintenance of existing cells
                                         Repair of damaged cells

What is cellular reproduction:
Enables parent cell to pass on genes & cell components to daughter cells

Process = cell division

Different organisms reproduce by


Cell division in prokaryotes

  1. Genetic information = single, circular dna
  2. Prokaryotic cell division = Binary fission
  3. DNA copying is first
  4. Protein ring forms
  5. Sep = cross wall forums
  6. One genome goes to each daughter cell.
  7. End result: 2 genetically identical daughter cells.

DNA: Organized in chromosomes
Accurate passage of genetic info is difficult.
Chromosomes help organize the process
remember:

Genes = code for protein
Genes = Sequences of nucleotides
           = Segments of dna double helix

Chromosome Contains:
Dna double helix
Centromere

Histones:  Proteins packaged with DNA (Chromatin)

DNA Orginsations:

Chromosomes occur in homologous pairs
Each homologue is same length and contains same genes in same order.

Diploid: cells with pairs of chromosomes (2n)
Found in most cells of the body