Unit 2: Genetic Processes Lesson 1.

BIG IDEAS FOR THE UNIT Genetic and Genomic research can have social and environmental implications Variability and diversity of organisms result from the distribution of genetic materials during the process of meiosis

Learning goals for this lesson Review cellular organelles structure/function Understand the steps in mitosis Understand the structure and organization of DNA, chromosomes and alleles

Some underlying concepts that will help you with this unit: All living things contain deoxyribonucleic acid (DNA). DNA, in humans, is located in the nucleus of all of our cells.* The DNA is arranged in the nucleus as organized packets known as chromosomes.

Humans have 46 chromosomes 23 chromosomes from each parent. Most cells (somatic) have the normal number of chromosomes, they are are said to be diploid (i.e. skin cells). Some cells have half the number of chromosomes are said to be haploid (i.e. egg and sperm cells).

The chromosomes from the parents are of the same type, just different variations, so each child has 23 pairs of similar chromosomes. 22 pairs are known as autosomes that contain important genes. The last pair are known as the sex chromosomes (X and Y) and they have fewer genes and more of an influence on gender.

On chromosomes are genes, organized sections of DNA that do one of the following: 1) Code for protein 2) Aid in the maintenance of an organism’s cells 3) Control a particular trait

Stuff you may not know… Genes that control traits (visible characteristics) have different variations called alleles. Since everyone has two copies of each chromosome, then each person has two alleles for a trait, one from each parent. The person responsible for the “discovery” of alleles is Gregor Mendel.

11 Mitosis Review In this lesson we will… learn about mitosis and meiosis (hopefully some of it will sound familiar!) identify important differences between these two processes compare and contrast sexual and asexual reproduction

12 Mitosis Mitosis is: the process where cells reproduce themselves Mitosis produces: 2 identical daughter cells Mitosis is important because: it ensures genetic continuity within an organism for growth, repair and development

G1 phase (growth): rapid growth and cell activity G2 phase: cell prepares for division

14 The Cell Cycle 2 main stages in the life cycle of a cell: 1.interphase: the cell is not dividing, this is where a cell spends 95% of its life 2.mitosis: where the cell divides, split into 4 stages i.Prophase ii.Metaphase iii.Anaphase iv.Telophase

15 Prophase Mitosis begins! Chromosomes coil up and take shape

16 Metaphase Step 2! Chromosomes align themselves along equatorial plate of the cell

17 Anaphase Step 3! Chromosomes split at the centromere and separate (spindle fibres contract) to opposite poles

18 Telophase Step 4! Chromosomes start to uncoil and decondense Cleavage furrow forms (not shown here) near the middle of the cell One cell becomes two

Identify the stages! 19

20 The stages of mitosis

Cytokinesis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes.

REMEMBER! I Interphase P Prophase M Metaphase A Anaphase T Telophase C Cytokinesis IPMATC I Pray M ore At T he Church

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24 - Cell Division 24

re=related ture=related Mitosis animations

Structure of DNA

Homologous Chromosomes

What is the sex of this individual? Karyotype