Biology IB Topic 3_ Genetics.pdf - Topic 3 Genetics Prokaryote and Eukaryote Chromosomes ● ● Eukaryotic chromosomes ○ Linear DNA molecule ○

Biology IB Topic 3_ Genetics.pdf - Topic 3 Genetics...

This preview shows page 1 - 3 out of 5 pages.

Topic 3: Genetics Prokaryote and Eukaryote Chromosomes Eukaryotic chromosomes Linear DNA molecule Associated with histone proteins No plasmids Two or more different chromosomes Prokaryotic chromosomes Circular DNA molecule No associated proteins Plasmids often present One chromosome only Chromatids Chromosomes in prophase and metaphase of mitosis consist of two structures known as sister chromatids Each sister chromatid contains a DNA molecule that was produced by replication during interphase, their base sequences are identical Sister chromatids are held together by a centromere Centromere divides in anaphase and allows chromatids to become separate chromosomes Homologous Chromosomes In humans, there are 23 types of chromosomes that each carry a different group of genes All the chromosomes of one particular type are homologous Haploid and Diploid Most plant and animal cells have a diploid nucleus, meaning that the nucleus contains pairs of homologous chromosomes Some cells have a haploid nucleus, which has only one chromosome of each type Sex Chromosomes Twenty-third pair of chromosomes determines whether individual is male or female XX = female XY = male Karyotypes and Karyograms Karyotype - number and type of chromosomes present in a cell or organism Two common uses of karyograms Deducing the sex of an individual (XX = female, XY = male) Diagnosing conditions due to chromosome abnormalities, if there are more or less than two chromosomes per pair, the person has a chromosome abnormality (e.g. 3 copies of chromosome 21 = down syndrome)
Image of page 1

Subscribe to view the full document.

Meiosis Fertilization - male and female gamete fuse together to produce a zygote Zygote has twice as many chromosomes as gametes Meiosis - a diploid nucleus divides twice to produce four haploid nuclei Meiosis and Genetic Variation Random orientation of pairs of homologous chromosomes in metaphase 1 For each pair of chromosomes, there are two possible orientations that
Image of page 2
Image of page 3
  • Fall '15
  • DNA, Chromosome Abnormalities

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern

Ask Expert Tutors You can ask 0 bonus questions You can ask 0 questions (0 expire soon) You can ask 0 questions (will expire )
Answers in as fast as 15 minutes