1. Genetic Processes
Unit 2

2. Questions to Ponder… Why do we resemble our parents?
What traits are inherited?
Why are the offspring of sexual reproduction not genetically identical to either parent?
Why is variation within a species important?
Why do we resemble our parents? (We resemble our parents because we inherit traits from them.) 2. Why does asexual reproduction result in genetic clones? (During asexual reproduction, the organism makes a copy of itself without combining its genes with those from another organism. The offspring are a genetic copy of the single parent.) 3. Why are the offspring of sexual reproduction not genetically identical to either parent? (During sexual reproduction, genes from two individuals combine to produce offspring with new combinations of genes.)

3. Activity: Variability- It Is a Coin Toss!
Purpose: to observe how random chance can influence genetic variation
Materials & Procedure: refer to Nelson Biology 11 page 137
Observations:
Round
Tail or Heads 1 2 3 4 5 6 7 8
Why do we resemble our parents? (We resemble our parents because we inherit traits from them.) 2. Why does asexual reproduction result in genetic clones? (During asexual reproduction, the organism makes a copy of itself without combining its genes with those from another organism. The offspring are a genetic copy of the single parent.) 3. Why are the offspring of sexual reproduction not genetically identical to either parent? (During sexual reproduction, genes from two individuals combine to produce offspring with new combinations of genes.)

4. Activity: Variability- It Is a Coin Toss!
Analysis:
How many students had a perfect match to one of the volunteers?
Were you surprised at how few sequences matched? Explain why or why not.
Was there greater variability in an individual coin toss, or in the sequences of eight coin tosses? Explain.
The number of possible sequences is 2n, where “n” is the number of tosses. How many different sequences of heads and tails are possible for eight coin tosses.
Calculate the number of possible sequences that could result from 23 coin tosses.
Why do we resemble our parents? (We resemble our parents because we inherit traits from them.) 2. Why does asexual reproduction result in genetic clones? (During asexual reproduction, the organism makes a copy of itself without combining its genes with those from another organism. The offspring are a genetic copy of the single parent.) 3. Why are the offspring of sexual reproduction not genetically identical to either parent? (During sexual reproduction, genes from two individuals combine to produce offspring with new combinations of genes.)

5. Genetics
heredity: process in which traits are passed from parents to offspring
genetics: the study of heredity and the variation of inherited characteristics

6. Genetic Material
when we “inherit” traits from our parents what we inherit is genetic information
DNA: a molecule that carries genetic information in cells

7. Genetic Material Cont’d…
gene: a segment of DNA that carries information for a specific trait
chromosome: a nuclear structure made up of DNA and protein on which all genes are located
locus: the location of a gene on a chromosome

8. Genetic Material Cont’d
chromosomes are found in the nucleus of all eukaryotic cells
When we “inherit” traits from our parents, what we actually inherit is genetic information. This genetic information is contained in segments of DNA called genes, and these genes are located at specific positions along chromosomes. Chromosomes, and all the genetic information they contain, are duplicated during cell division. You will learn more about how this information is passed on to offspring throughout the course of this unit.

9. Chromosomes
different types of organisms have different types and numbers of chromosomes (ex. humans have 46 chromosomes per cell and dogs have 78)
Some organisms have few chromosomes in their body cells, while others have many chromosomes in each body cell. Most multicellular organisms have less than 100 chromosomes in the nucleus of each body cell (Table 1).

10. Chromosomes Cont’d…
in most multicellular organisms, chromosomes occur in sets
diploid cells (2n): have two sets of chromosomes
haploid cells (n): have half the normal number of chromosomes
polyploids: cells that contain three or more sets of chromosomes
Some organisms have few chromosomes in their body cells, while others have many chromosomes in each body cell. Most multicellular organisms have less than 100 chromosomes in the nucleus of each body cell (Table 1).

11. Asexual Reproduction
asexual reproduction: the production of offspring from a single parent
occurs through cell division
the chromosomes of the parent cell are duplicated and divided so that each of two daughter cells receives one copy of each chromosome
result is two new cells that are genetically identical to one another and to the parent cell
Known as the “mother of thousands” plant, Kalanchoe daigremontiana produces asexual “baby” plants along the edges of its leaves.

12. Sexual Reproduction
Sexual Reproduction: production of offspring from the fusion of two sex cells (usually from two different parents)
half of their genetic information is from each of their two parents
the genetic makeup of the offspring is different from that of either parent and are rarely genetically identical to each other

13. Advantages and Disadvantages Of Asexual Reproduction
do not have to seek out a mate
do not have to perform specialized mating behaviours
possess specialized anatomy
nothing is left to chance
Disadvantages:
if and when the environment changes, the individuals may not be well adapted to survive
Known as the “mother of thousands” plant, Kalanchoe daigremontiana produces asexual “baby” plants along the edges of its leaves.

14. Advantages and Disadvantages Of Sexual Reproduction
must have specialized organs to produce sex cells
sex is biologically “costly” and potentially risky (ex. producing flowers attracts pollinators like bees, but also requires the production of nectar)
possible that the offspring may inherit a combination of genetic information that makes them weak and unable to survive
Figure 4 (a) An adult male moose grows a new and impressive set of antlers each year. Energy and nutrients are required for this process. (b) A peacock (a male peafowl) grows ornate tail feathers to attract peahens. This can be a disadvantage when it comes to avoiding predators.

15. Advantages and Disadvantages Of Sexual Reproduction Cont’d…
variability increases the chances of a species surviving changes in the environment (ex. fire, volcanic eruption, disease, climate change, evolution of a new species)
some offspring may not be well adapted for change, while others may have traits that allow them to adapt to a new environment
Why, then, do so many of Earth’s organisms participate in some form of sexual reproduction? What is it about producing genetically variable off spring that creates a benefi t worth the cost in time, energy, and resources?

16. Homework
answer 4.1 questions 1-9