1. The Continuity of Life

2.  Necessary for species to survive  Species ◦ Closely related organisms that share certain characteristics and can produce new individuals through reproduction

3.  New organisms go through stages and grow into adulthood

4.  Division of the NUCLEUS! ◦ Asexual (mitosis) ◦ Sexual (meiosis)

5. Growth, repair, replacement of cells To form sex cells (sperm and eggs) for reproduction  1 parent  1 division (2 cells)  Identical offspring  Rapid and high #  2 parents  2 divisions (4 cells)  Varied offspring  Slower and low #

6.  A series of events that occur in the life of a cell ◦ Growth ◦ Preparation for division ◦ Division

7.  DNA: genetic material found in the nucleus of cells  Chromosome: organized structures of DNA and proteins found in cells  Chromatid: coiled DNA (forms ½ of the “X” shape)  Centromere: holds sister chromatids together

8.  Chromatin: uncoiled DNA (looks like spagetti)  Haploid: one set of chromosomes (in humans 23)  Diploid: double set of chromosomes (in humans 46)  Gametes: sex cells (sperm and eggs)

9.  Splitting of 1 cell into 2 cells evenly

10.  1 parent cell splits into 2 cells (unevenly)

11.  Mold spore cells reproduce mold (on the underside of leaves or on food)

12.  Re-growth of a body part

13.  Runners: strawberries  Tubers: potatoes from stems  Bulbs: underground stem  Cutting: part of a plant gives rise to a new plant  Grafting: part of one plant attached to another

14.  NUCLEAR DIVISION! ◦ Nuclei divide to form 2 identical nuclei with the same # of chromosomes ◦ Cytoplasm pinches and divides to form 2 daughter cells

15.  IN between divisions  Period of growth for a cell when it replicates its DNA and centrioles and prepares for division  Longest period during the cell cycle  Divided into: ◦ G1 – Growth ◦ S – Synthesis of DNA (duplication) ◦ G2 – Growth and preparation for division

16.  Prophase  Metaphase  Anaphase  Telphase  Cytokinesis – occurs after Telophase but is not technically part of mitosis because the nucleus has already divided

17.  Chromatin condenses and coils into chromosomes  Centrioles separate  Spindle apparatus forms  Nuclear membrane breaks down

18.  Chromosomes line up across the center (midline)  Each chromosome is connected to a spindle fiber at its centromere

19.  Sister chromatids separate  Individual chromatids are moved to the poles (corners) of the cell.

20.  Chromosomes gather at opposite ends of the cell  Chromosomes loose their shape  2 nuclear membranes form

21.  Cytoplasm pinches in half (cleavage) and divides  Each daughter cell has an identical set of chromosomes (diploid)  Not part of mitosis

22.  Offspring receive half of their DNA from 1 parent and half form the other  No 2 organisms are exactly the same!  The same to people will continue to produce offspring that have different combinations of DNA  DNA is transferred by sex cells (gametes)

23.  Nuclear division of cells to create 4 daughter cells with a haploid (half #) set of chromosomes.  Used to produce SPERM AND EGGS for sexual reproduction (Gametogenesis)  2 Divisions to divide the # of chromosomes in half

24.  Chromosomes line up in pairs (diploid)  1 st division (similar to mitosis)  2 nd division (reduces chromosomes to ½)  Each daughter cell is haploid Differentiate into 4 sperm with different combinations of chromosomes

25.  Chromosomes line up in pairs (diploid)  1 st division (similar to mitosis)  2 nd division (reduces chromosomes to ½)  Each daughter cell is haploid Differentiate into 3 polar bodies and 1 viable egg

26.  The sorting of genes and recombining them during meiosis and fertilization creates variety ◦ Variety is important for the survival of species  Mutations or changes in the chromosomes can only be passed on to offspring if it occurs in the sex cells  DNA can be further varied during crossover in prophase 1

27.  Joining of sperm and egg (haploid)  Forms a zygote (diploid)  Can be external or internal

28.  Growth of a new organism from fertilization into adulthood

29.  Fish and amphibians ◦ Lay eggs and release sperm in the water ◦ Large number of eggs are released to ensure survival ◦ Risky! ◦ Low survival rate ◦ Development occurs in the water

30.  Land animals – sperm is deposited in the body of the female ◦ Birds and reptiles:  Fertilization occurs (forms eggs)  Eggs continue to develop externally with some parental care  3-7 eggs to ensure survival ◦ Mammals:  Fertilization occurs and development is internal  Lots of parental care  1-3 zygotes – high survival rate

31.  Zygote divides by mitosis to grow and become a developed multi-cellular organism  Early cells are identical to eachother (stem cells)  Stem cells can become any type of cells (like a blank slate)  Brain Pop video: Stem CellsStem Cells

32.  Cells continue to divide and genes are activated or “turned on” creating different types of cells  Differentiated cells become specialized cells and tissues for form specific body organs and systems

33.  All cells in an organism contain the exact same DNA  Genes are activated in certain cells to specialize  Environmental factors can determine which genes are activated and how they are expressed

34.  Cells divide through mitosis  3 layers form an embryo ◦ Ectoderm (outer) – skin, hair, nails, nerves ◦ Mesoderm (middle) – bones, muscles, blood ◦ Endoderm (inner) – abdominal organs

35.  In water ◦ Little or no parental care  On land ◦ Some parental care ◦ Differentiated layers form a protective shell that cushions and supports the embryo ◦ Yolk is the food source for the embryo

36.  Mammals ◦ Embryo develops within the mother’s uterus ◦ Receives nutrients from the placenta ◦ High survival rate = less offspring

37.  Develops within the uterus during pregnancy  Umbilical cord connects the mother to the fetus  Exchange of nutrients, gases and waste  The mother’s blood and baby’s blood are never in direct contact

38.  Organized profile of a person’s chromosomes  Cell division is suspended at metaphase  Chromosomes are cut and arranged by size from largest to smallest  44 autosomes  2 sex chromosomes (XX or XY)  Arrangement helps doctors and scientists identify chromosomal abnormalities that may result in a genetic disorder

40.  An extra 21 st chromosome (trisomy 21)is received during mitosis (the 21 st chromosome fails to separate during anaphase and the daughter cell ends up with 24 chromosomes instead of 23)  The child now has 47 chromosomes instead of 46  Affects 1 in every 800 babies born  Symptoms include: short stature, weak muscles, short/wide neck, characteristic facial symptoms, intellectual disability and heart defects

42.  Extra “x” chromosome  Affects 1 in every 700 males  Signs include: lower IQ, slower development and reduced fertility

43.  Single “x” chromosome  Affects 1 in 2000 girls  Signs include: short stature, broad chest, non-working ovaries, amenorrhea, heart disease and memory deficiencies