Sexual reproduction and the diversity of life
Download
1 / 20

Sexual Reproduction and the Diversity of Life - PowerPoint PPT Presentation


  • 125 Views
  • Uploaded on

Sexual Reproduction and the Diversity of Life. BC Science Probe 9 Section 3.2 Pages 79-82. Fertilization Produces Diploid Cells. Fertilization: The joining or fusing of two gametes. Gametes are produced by meiosis

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Sexual Reproduction and the Diversity of Life' - kordell


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Sexual reproduction and the diversity of life

Sexual Reproduction and the Diversity of Life

BC Science Probe 9

Section 3.2

Pages 79-82


Fertilization produces diploid cells
Fertilization Produces Diploid Cells

  • Fertilization: The joining or fusing of two gametes.

    • Gametes are produced by meiosis

    • They are haploid (only have ½ the regular number of chromosomes of the parent cell)

    • When two gametes fuse during fertilization, they make a diploid cell (a cell with a full set of chromosomes)


Fertilization produces diploid cells1
Fertilization Produces Diploid Cells

  • The first diploid (2n) cell of the offspring is called the zygote.

    sperm(n) + egg (n) = zygote (2n)


Fertilization produces diploid cells2
Fertilization Produces Diploid Cells

  • Zygote:

    • Gets half of its chromosomes from each parent.

    • Human gametes each have 23 chromosomes, so a human zygote will have 46, then divide by mitosis to produce more genetically identical cells with 46 chromosomes


Diversity among offspring
Diversity Among Offspring

  • Diversity = variation or differences

  • There is diversity among different species and also within a species.

  • Sexual reproduction creates diversity


Diversity among offspring1
Diversity Among Offspring

  • It’s the homologous pairs of chromosomes that produce the variations among members of a species.

    • Each of the chromosomes in the homologous pair have corresponding genes (genes that code for the same trait ex. hairline)

    • But… these genes can be slightly different from one another!


Diversity among offspring2
Diversity Among Offspring

  • The different forms of the same gene are called alleles.

    • Back to the hairline example: there are two different alleles.

      • One is for a straight hairline

      • One is for a widow’s peak


Diversity among offspring3
Diversity Among Offspring

  • The allele for a widow’s peak is dominant.

    • This means that it will express its trait (show up) if it is present


Diversity among offspring4
Diversity Among Offspring

  • The allele for a straight hairline is recessive.

    • This means that it will only show up if both chromosomes in the homologous pair have the recessive allele.


Diversity among offspring5
Diversity Among Offspring

  • If an individual has one of each allele, the dominant one gets expressed.


Diversity among offspring6
Diversity Among Offspring

  • Some alleles are not dominant or recessive.

  • There are such things as incomplete dominance and codominance.


Diversity among offspring7
Diversity Among Offspring

  • Incomplete dominance:

    • Two different alleles produce a mixture of the traits.

    • Red carnation + white carnation = pink carnation


Diversity among offspring8
Diversity Among Offspring

  • Codominance is when both traits get expressed.

    • This horse has one allele for white hair and one for red. Both get expressed.


Diversity among offspring9
Diversity Among Offspring

  • There are even some traits that are controlled by more than one gene!

  • Human eye colour is one of these traits. That’s why there are so many variations!


ad