Chromosomes Boogie

Chromosome Condensed form of chromatin A threadlike structure of nucleic acids and protein Always paired with an identical copy of itself

SISTER CHROMATIDS CHROMATID

Chromosome

Types of Chromosomes Autosomes The 1 st 22 pairs of chromosomes in humans. Sex Chromosomes 23 rd pair In females, the sex chromosomes are the 2 “X” chromosomes. Males have one “X” chromosome and one “Y” chromosome. –The Y chromosome is what makes a baby boy.

Types of Cell Division Asexual: Offspring are identical to parents Examples: Budding: yeast : Binary Fission: bacteria Sexual: Offspring have a combination of genetic information from 2 parents (s perm and egg) Examples: Animals and plants

Numbers of Chromosomes Haploid: Cells with 1 set of genetic info Ex: sperm and eggs Diploid: Cells with 2 full sets of genetic info Ex: body cells Two Haploid cells unite to make Diploid Cells Aka: Zygote

Why do cells divide? 1.Growth 2.Reproduction (Development) 3.Repair or Replace

What Happens in Cell Division Replicates the DNA exactly. Movement of the two copies of DNA to opposite ends of the cell. Separates into two daughter cells.

Cell Cycle Interphase –The phases that prepares cells for Mitosis –Chromosomes appear as threadlike coils (chromatin) –90% of cell cycle –Three phases 1.G1 - Growth 2.S - DNA Replication 3.G2 - Growth (prepares to divide)

Mitosis 1 cell becomes 2 cells -both new cells are identical to the original -(all cells except sperm & eggs do this)

Mitosis Cell division occurs in a series of 4 stages, or phases. –Stages 1.Prophase 2.Metaphase 3.Anaphase 4.Telophase

Prophase Mitosis begins (cell begins to divide) You can see chromosomes start to form

Metaphase Chromosomes line up in the center of the cell

Anaphase Chromatids or chromosomes separate and begin to move to opposite ends of the cell

Telophase Two new nuclei form Chromosomes appear as chromatin Mitosis ends

Cytokinesis Become two identical new cells Half the size of the original

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What Stages of Mitosis can you find?

Meiosis 1 cell becomes 4 cells called gametes Male gametes = Sperm Female gametes = Eggs

Meiosis is Mitosis twice without Interphase in between & Mitosis Mitosis is in my toes, but Meiosis Meiosis is in my ovaries The Difference? The Difference?

Why Meiosis? Fertilization –Union of haploid sperm and egg (n) –Diploid Zygote is formed (2n) The chromosome number is reduced, so at fertilization there is the correct # of chromosomes.

Why Meiosis? Cuts chromosome number in half by separating homologous chromosomes –Homologous Chromosomes: occur in pairs and have the same genetic information, one inherited from mom and one from dad. Creates variation for Evolution Makes offspring unique

Meiosis creates variation in 3 ways 1) Law of Segregation chromosome pairs separate during meiosis 2) Law of independent assortment genes are separated randomly (shuffle) 3) Crossing Over chromosome parts break off & reattach to other chromosomes creates new chromosome

Crossing Over

Mitosis vs. Meiosis Mitosis Creates Diploid Cells (2N) 1.Cells with 2 full sets of genetic info 2.Human body cells have 46 chromosomes each (diploid or 2N # is 46) 3.Happens in Somatic Cells (body cells) and make up the entire organism expect the sperm and eggs Meiosis Creates Haploid Cells (N) 1. Cells with 1 set of genetic info 2. Human sperm & eggs have 23 chromosomes (haploid or N # is 23)

MITOSIS MEIOSIS

Meiosis (Go back to Table) InterphaseInterphase (approx 90% of time) – DNA Replication Prophase 1Prophase 1 Tetrad (chromosome pair) forms –Crossing over occurs Metaphase 1Metaphase 1 –Chromosomes move to midline Anaphase 1Anaphase 1 –Homologous chromosomes separate Anaphase 2Anaphase 2 –Sister chromatids separate The Rest is Just Like Mitosis

The Differences MitosisMeiosis 1 cell becomes… 24 Cell TypesIn my__________ Haploid or Diploid Why/Importance Phases PMAT Diagram

Chromosomes How do we look at the chromosomes of an individual? The collection of chromosomes found in an individual’s cells

Chromosomes How is it made?How is it made? 1.Chemically treated to stop them in metaphase (from blood or amniotic fluid) 2.Chromosomes are stained 3.The chromosomes are then photographed 4.Chromosomes are cut out 5.Arranged in pairs from largest to smallest 6.Chromosomes are numbered in 23 sets

#2 Chromosome Scatter #3 Karyotype #1-Chromatin

Chromosomes Abnormalities 1.Nondisjunction (NOT-COMING-APART) Chromosomes fail to separate during anaphase of Meiosis 2. Mutations: changes in chromosome structure

Nodisjunctions What if a chromosome is missing? –Most do not survive to be born –If a chromosome is missing the condition is called Monosomy EX: Turner’s Syndrome (XO)

Nondisjunctions What if a cell has an extra chromosome? –The condition in which a cell has an extra chromosome is called Trisomy –Example: Trisomy 21 (Down Syndrome)

Nondisjunction TRISOMYMONOSOMYNORMAL Chromatids do not Separate in Anaphase II

Mutations Deletion part of the chromosome breaks off Duplication: part of the chromosome is repeated

Cancer Mutations in genes that control normal cell division can lead to cancer. Increasing your risk Increasing your risk Sun without sun block Smoking or being around 2 nd hand smoke Working with known cancer causing chemicals. Eating foods with preservatives such as nitrates Cooking Foods in plastics that contain dioxin

Proto-Oncogenes Proto-Oncogenes are normal genes that code proteins involved in a cell's normal growth Oncogenes Oncogenes tell cells to make proteins that cause excessive cell growth and division. *Oncogenes are Mutant Forms of Proto-Oncogenes*

Normal genes whose ABSENCE can lead to cancer. Why don’t we all get cancer? Genes come in pairs, one from each parent A defect in one copy will not cause cancer because the other normal copy is still functional. Tumor Suppressor Genes