* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Meiosis - BiologyGerlach
Genomic imprinting wikipedia , lookup
Genealogical DNA test wikipedia , lookup
Genomic library wikipedia , lookup
Polycomb Group Proteins and Cancer wikipedia , lookup
Site-specific recombinase technology wikipedia , lookup
No-SCAR (Scarless Cas9 Assisted Recombineering) Genome Editing wikipedia , lookup
Cell-free fetal DNA wikipedia , lookup
Comparative genomic hybridization wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Birth defect wikipedia , lookup
History of genetic engineering wikipedia , lookup
Genome (book) wikipedia , lookup
Extrachromosomal DNA wikipedia , lookup
Point mutation wikipedia , lookup
Designer baby wikipedia , lookup
Hybrid (biology) wikipedia , lookup
Y chromosome wikipedia , lookup
Microevolution wikipedia , lookup
X-inactivation wikipedia , lookup
Meiosis Biology 2009-2010 Meiosis • Def: type of cell division that produces 4 cells with half the number of chromosomes as a parent cell • Occurs in the sex organs • Number of chromosomes= 46 or 23 pairs Homologenous Chromosomes • Def: chromosomes that match in shape and size but not necessarily same DNA patterns Homologous Chromosomes • Karyotyping – Def: arrangement of all 46 chromosomes • Sex chromosomes – The 23rd pair – Determines the organisms sex – XX= girl – XY=boy Diploid vs. Haploid • Diploid – 2 homologenous sets of chromosomes – Forms the zygote – 2n • Haploid – 1 set of chromosomes- one from each pair – Occurs in fertilization –n Number of Chromosomes • Sex Cells each have half the number of chromosomes (23) • Zygote (fertilized egg) have 46 chromosomes Steps of meiosis • Differences between mitosis and meiosis: – Meiosis produces 4 offspring cells – Meiosis involves exchanging of genetic material between the Homologous Chromosomes. • Sister chromosomes- exact copies of DNA • Homologenous chromosomes- DNA does not have to be the same Meiosis 1 • Prophase 1 – Homologenous chromosomes stick together forming a tetrad – Crossing over begins • Metaphase 1 – Crossing over is complete – Chromosomes line up in the center • Anaphase 1 – Chromosomes migrate towards the opposite poles • Telophase 1 – Each pole has a haploid Crossing Over • DEF: Genetic materials is transferred from one chromosome to another Cross ed over Meiosis 2 • Follows the exact same steps as Mitosis except the end results in 4 cells instead of 2 Chickens have 78Cats chromosomes have in their body cells how 38 many chromosomes dochromosomes they have in their sex cells? in their diploid cells. How many do they have in their haploid cells? Birth Defects Biology2009-2010 Numbers • There are 200,000 people born with birth defects every year • To break it down, there are 25 people born with birth defects per hour Causes of Birth Defects • Drugs/Alcohol/Smoking • Radiation/Pollution • STD’s • Inheritance • Malnutrition Detection • Blood Test • Amniocentesis– A sample of the amniotic fluid is taken and then the DNA is checked for Chromosomal defects Chromosomes • Monosomy- loss of one chromosome • Trisomy- gain an extra chromosome • Sex Chromosomes- X and Y Down Syndrome • Occurrence-1/600 births • Causes- trisomy 21 • Chance with increased age – 20’s- 1/1500 – 40’s-1/44 Homozygous Recessive Traits • Found on the X chromosome • Passed on from mother’s to their children • Examples: Muscular Dystrophy and color blindness Mutations • Definition- change in the DNA by changing one or more genes Mutagens • Definition- Agents that cause mutations • Examples: Chemicals, x-rays, radiation, genetic Twins • Fraternal- Two fertilized eggs are implanted in the uterus at one time • Identical- one fertilized egg that splits