2024 AAC Karyotypes And Meiosis Slide Notes PDF

Meiosis & Karyotypes Click link to advance topic  Meiosis Observations Questions Initial Model Unidentical Twins (What do you (What do you still (describe or notice?) have questions draw)...

Meiosis & Karyotypes Click link to advance topic  Meiosis Observations Questions Initial Model Unidentical Twins (What do you (What do you still (describe or notice?) have questions draw) about?)  Prompt 1 Reading ❖ Identify: The name of the process that increases genetic variation. How do the same parents create ❖ Provide: 2-3 differences between mitosis and meiosis. offspring (kids) that ❖ Define: haploid & diploid look so different? Click to open the reading Sentence Stems: I believe the variation in offspring can be attributed to … The differences in offspring is due to… Exploring Meiosis Meiosis Notes AAC Review of Mitosis ★ Purpose: grow, repair, replace ★ End Product: genetically identical diploid cells ○ Diploid - two copies of each chromosome (2N) Introduction to Meiosis ★ Purpose: produce sex cells (gametes → sperm & egg) ★ End Product: genetically diverse haploid cells ○ Haploid - one copy of each chromosome (N) A Review of Chromosomes Chromosomes - in detail ★ Somatic Cell (body cell) ○ 46 chromosomes 22 homologous pairs (autosomes) 1 sex chromosome pair ○ Diploid (2N) 1 set from mother, 1 set from father Chromosomes - in detail ★ Homologous Chromosomes ○ Same size, same shape ○ Carry the same type of genetic information (same genes in the same place) ○ Carry genes that control the same inherited traits ○ One homolog is from the mother, one is from the father Chromosomes - in detail ★ Germ Cell (sex cell, gamete) ○ 23 chromosomes 22 autosomes 1 sex chromosome ○ Haploid (1N) 1 set of chromosomes - a combination of mother’s + father’s genetic contribution Chromosomes - in detail Chromosomes - in detail ★ When gametes combine during fertilization, the number of homologous chromosomes is restored Pre-Meiosi s Interphase ★ ○ Organelles and chromosomes replicate ○ Cell prepares to divide ○ Chromatin begins to condense Meiosis I - Steps ★ Prophase I ○ Nuclear membrane disappears ○ Spindle fibers appear ○ Homologous chromosomes are paired → tetrads form ○ Crossing over occurs Meiosis I - Steps ★ Prophase I ○ Tetrads - pairing up of homologous chromosomes ○ Crossing over - the exchange of genetic information between homologous chromosomes Contributes to genetic diversity! Meiosis I - Steps ★ Metaphase I ○ Tetrads/homologous chromosomes line up in the middle of the cell ○ Spindle fibers attach to centromeres Meiosis I - Steps ★ Anaphase I ○ Spindle fibers pull apart tetrads → move toward opposite poles of dividing cell ○ Independent Assortment - one set of homologous chromosomes lines up and separates independently from others Meiosis I - Steps ★ Anaphase I ○ Independent Assortment Meiosis I - Steps ★ Telophase I ○ Spindle fibers break down ○ Chromosomes uncoil and form two nuclei ○ Nuclear membranes and nuclei reform ○ Cell splits into two NON-IDENTICAL cells THINK ABOUT ITDoes interphase occur between meiosis I & meiosis II? ★ Meiosis II - Steps ★ Prophase II ○ Spindle fibers form ○ Nuclear membrane disappears ○ NO crossing over WHY? Meiosis II - Steps ★ Metaphase II ○ Sister chromatids line up in the middle of the cell Meiosis II - Steps ★ Anaphase II ○ Sister chromatids are pulled apart at the centromere by the spindle fibers ○ Sister chromatids move to the opposite poles of the dividing cell Meiosis II - Steps ★ Telophase II ○ Nuclear membrane and nuclei reform ○ Spindle fibers disappear ○ Cell begins to split into 4 cells Meiosis II - Steps ★ Cytokinesis ○ Four haploid daughter cells are formed n number of chromosomes Meiosis II - Steps ★ Cytokinesis ○ Four haploid daughter cells are formed n number of chromosomes Meiosis II - Steps ★ Spermatogenesis ★ Male Cytokinesis ○ End result is 4 equal cells that develop heads and tails Importance of Meiosis ★ Oogenesis ★ Female Cytokinesis ○ Division of cytoplasm is uneven ○ One cell receives most of the cytoplasm to become the mature egg; the other 3 are known as polar bodies and usually die Importance of Meiosis ★ Provides genetic variation ○ Crossing over during Prophase I ○ Independent Assortment- Alignment and separation of chromosomes during Metaphase I/II and Anaphase I/II Comparing Mitosis and Meiosis  Meiosis Looping Back to the Anchoring Phenomenon What causes these twins to look so different?  Welcome Back! Final Exam Review Sheet is now available in CANVAS. Due: Friday, December 13th (for +5 bonus on final) → Submitted to CANVAS by the end of your class period Formative Additional Review : Biology PSA KARYOTYPES What is meant by the word homologous?  TYPES OF CELLS all body cells sex cells (sperm/egg) Diploid Haploid Contains 46 Contains 23 chromosomes chromosomes  KARYOTYPES ★ An organized grouping of an individual's chromosomes. ★ They are dyed and organized based on size in order to study.  Who has a karyotype done? ★ Many parents often choose to have genetic testing done on their unborn baby to look for any abnormalities in their chromosomes.  THE X AND Y CHROMOSOMES ★ An organism’s sex is an inherited character determined by the presence or absence of certain chromosomes ★ Humans and other mammals: two varieties of sex chromosomes, X and Y ★ The last pair of chromosomes (#23) are the sex chromosomes. These determine the genetic gender. ★ If you have one X chromosome what is your genetic gender? ★ The sex chromosomes are circled. ★ Chromosomes 1-22 are called autosomes and control non sex-linked traits. ★ Since females have two X chromosomes (XX) they can only give an X to their offspring. ★ Males have an X and a Y chromosomes, so they can either give the X or Y. ★ Who determines the sex/genetic gender of the baby? ★ This is a karyotype of a human male. ★ What information lets us know that?  Chromosomes by the numbers: Chromosomes by the numbers: 46 ____Total chromosomes 23 ____Total pairs of chromosomes 44 ____Total autosomal chromosomes 2 ____Total sex chromosomes 22 ____Homologous pairs 22 ____Autosomal homologous pairs 23 ____number of chromosomes in gamete 0 ____number of pairs in gamete 1 ____number of sex chromosomes in gamete  Find the numbers by using a karyotype Chromosomes by the numbers: 40 ____Total chromosomes 20 ____Total pairs of chromosomes 38 ____Total autosomal chromosomes 2 ____Total sex chromosomes 19 ____Homologous pairs 19 ____Autosomal homologous pairs 20 ____number of chromosomes in gamete 0 ____number of pairs in gamete 1 ____number of sex chromosomes in gamete  GENETIC ABNORMALITIES Notice anything unusual? What’s the chromosomal abnormality?  NONDISJUNCTION ★ Homologous Chromosome pairs or sister chromatids fail to separate correctly during cellular division ★ Can occur in both Mitosis and Meiosis Chromosomal Mutations COPY THIS IMAGE INTO YOUR NOTES.  Human Examples of Chromosome Mutations ⋆ Deletion ⋆ Cri du Chat (missing part of chromosome 5) ⋆ Turner Syndrome (missing an X chromosome) ⋆ Duplication ⋆ Some cancers ⋆ Pallister Killian- muscular issues, feeding, breathing ⋆ Translocation ⋆ Leukemia ⋆ Inversion ⋆ Hemophilia  ANEUPLOIDY ★ Aneuploidy results from the fertilization of gametes in which nondisjunction occurred ○ Trisomic zygote has three copies of a particular chromosome ○ Monosomic zygote has only one copy of a particular chromosome  ANEUPLOIDY IN HUMANS ★ Trisomy 21 ○ Down syndrome ★ Monosomy ○ Turner Syndrome is the only known monosomy in humans that is not fatal Polyploidy is a condition in which an organism has more than two complete sets of chromosomes 2n Diploid 4n Tetraploid  POLYPLOIDY IN HUMANS ★ Is lethal in humans ★ Some cells in critical tissue like the liver and placenta will have cells that are polyploidy. ○ Around 30% of liver cells exhibit polyploidy (either by extra copies of chromosomes in the nucleus, or by having multiple nuclei) One reason theorized is to increase the number of tumor suppressor genes. ★  Polyploidy in other animals ★ Some fish, amphibians and insects show polyploidy. Fisherman love to catch polyploidy trout because of their large size. PLANT POLYPLOIDY  POLYPLOIDY & ARTIFICIAL SELECTION ★ Plant breeders often take advantage of these mutations. ○ EX: In meiosis a set of chromosomes sometimes fails to separate and produce gametes that are triploid (3N) or tetraploid (4N) → these plants are often stronger and larger.  We love mutated fruit!  KARYOTYPE ACTIVITY ★ You will have to count chromosomes ★ Observe mutations ★ Research disorders ★ Identify individuals with that disorder KARYOTYPE PRACTICE (GDoc Notes)  Emily 64 Or Tammy