1. Generating New Generations

2. Reproduction and Growth
All living things reproduce
Reproduction guarantees that a species’ genes are passed on to the next generation
Organisms use one of two main methods to produce offspring- asexual and sexual reproduction

3. Asexual Reproduction Simplest form of reproduction
Involves only one parent
Offspring only inherit the genes from of that parent
Produce offspring that are genetically identical to the parent
Examples:
Animals such as corals, starfish, sponges, and certain jellyfish
Many plants, fungi, bacteria, and protozoans

4. Types of Asexual Reproduction
Budding- Offspring grows from the parent until it fully matures and breaks off (ex. corals, sponges, and sea anemones)
Fission- The cell’s contents are replicated internally and then divides into two distinct entities (ex. single cell organisms like prokaryotes and some protozoa)
Fragmentation- New organism forms from a piece of the original (ex. new sea star may form from an arm that breaks off)

5. Types of Asexual Reproduction
Parthenogenesis- Female organisms produce female offspring within their bodies without being fertilized by a male (ex. some amphibians)
Spores- Parent releases spores that develop into fully grown organisms when conditions are environmentally suitable (ex. some protozoans, bacteria, plants, and fungi)
Vegetative- Some plants use specialized genetic features that allow them to reproduce without seeds or spores (ex. aerial stems of strawberries, bulbs of tulips, and the tubers of potatoes)

6. Sexual Reproduction
Two parents combine their genetic material to produce a new organism
Offspring are not exact copies of the parents, instead they display traits which differ from both parents
Responsible for the variety of life on our planet

7. Sexual Reproduction Forms New Cells
During fertilization an egg and a sperm cell join to form a new cell
Each egg cell and sperm cell contains half of the parent’s chromosomes
When fertilization occurs, a full set of chromosomes is present in the new cell
Results in a combination of specific characteristics known as traits
Traits are passed to an offspring by a sequence of DNA on the chromosomes known as genes
Create the individual variations found in the offspring

8. Comparing Types of Reproduction Advantages
Advantages of Asexual Reproduction
Advantages of Sexual Reproduction
Can produce offspring quickly-
-Useful for species who’s survival strategy
is to reproduce fast (ex. bacteria)
Offspring have greater genetic variations-
-Creates diversity
Doesn’t require a mate-
-Enables isolated species to create offspring
2. Promotes survival-
-Offspring may inherit a gene that helps them
adapt to changing environments
Requires less resources-
- Many sea creatures and plants create
offspring by cutting off part of themselves
3. Removes “bad genes” from the population

9. Comparing Types of Reproduction Disadvantages
Disadvantages of Asexual Reproduction
Disadvantages of Sexual Reproduction
Lack of diversity-
-With the exception of rare mutations,
offspring are identical to their parent
Require a mate-
-Can be a problem for organisms living in
isolated or remote areas
2. Organisms are more susceptible to diseases and
environmental hardships-
-If one individual organism is unable to
tolerate a disease or change, chances are the
other identical offspring wont either
Takes time and energy-
-Finding a mate, courtship
3. Produces fewer offspring
Can prevent “favorable genes” from being
passed to an offspring

10. Heredity and Gregor Mendel
Heredity- the passing of traits from parents to offspring
Gregor Mendel- Austrian monk known as the “Father of Modern Heredity”
Studied heredity by cross-pollinating pea plants, from 1856 to 1863, at the monastery where he tended the gardens
Experimented with 7 characteristics of pea plants (plant height, pod shape & color, seed shape & color, and flower position & color)

11. Mendel’s Research Mendel formulated several ideas about heredity
Through experimentation, he realized that certain patterns, in the passing of characteristics (traits), formed from the parent plants to their offspring
Mendel called the information that carried the traits factors (now referred to as genes or alleles), because they determined what was expressed

12. Mendel’s Conclusions
Mendel determined that for every trait, organisms receive one factor from their mother and one from their father
Concluded that one factor could mask the expression of the other, even if both were present at the same time
Coined the terms “dominant” and “recessive” in reference to certain traits
Dominant factors would mask the expression of recessive factors if both were present at the same time
Concluded that while only one form of a trait was visible in the offspring, the missing trait sometimes shows itself in later generations

13. Inheriting Traits
When egg and sperm cells come together, genetic information from the parents mix
Inheritance is the process by which an offspring receives genes from its parents
Genes are located on chromosomes and describe the factors that control a trait
Each trait is described by a pair of genes, with one gene from the mother and the other from the father

14. Gene Pairs
Sometimes the genes in a pair are both the same, and at other times, they are different from each other
An allele is a different form of the same gene
One allele is inherited from each parent, their combination determines which traits the offspring will have

15. Dominate vs. Recessive Alleles
Alleles are either dominate or recessive
A dominate allele is represented with a capital letter
A recessive allele is represented with a lower case letter
If an offspring inherits a dominant allele from either parent, that dominant trait will always show up in the offspring
Offspring must inherit a recessive allele from both parents in order for the recessive trait to show

16. Expressing Traits
In plants, T often represents a dominate allele for tall and t a recessive allele for short
Purebred- Organism has two of the same allele for a trait (TT or tt)
Also referred to as being homozygous
Offspring inherited the same type of allele from both parents
TT (homozygous dominant) all tall offspring
tt (homozygous recessive) all short offspring
Hybrid- Organism has one dominant and one recessive allele for a trait (Tt)
Also referred to as heterozygous
Offspring inherited a different type of allele from each parent
Tt all offspring will be tall

17. Multiple Alleles
Multiple alleles- Occurs when a trait has more than 2 alleles
Each parent still contributes an allele which will combine to create the trait expressed in the offspring
With additional number of alleles, the number of possible outcomes increases
For Example, there are three types of alleles for blood type (A, B and O)
The A and B blood types are codominant and O is recessive
This results in four blood types are A, B, AB, and O

18. Incomplete Dominance & Codominance
Incomplete dominance- Occurs when an intermediate form of a dominant trait appears
The offspring have a mixture of the two alleles
Ex. A plant with red flowers is crossed with one with white flowers, resulting in offspring with pink flowers
Codominance- Occurs when two different alleles for the same gene are expressed at the same time (neither allele acts as dominant or recessive)
Ex. A plant with red flowers is crossed with one with white flowers, resulting in offspring having red flowers with white stripes

19. Genotypes and Phenotypes
Genotype- An organisms genetic make up or combination of alleles
The set of genes in an organism’s DNA which are responsible for a particular trait
Ex. In plants, possible genotypes for height could be TT, Tt, or tt
Phenotype- An organisms appearance or visible traits
The physical expression, or characteristics, of inherited traits
Ex. In plants, possible phenotypes for height could be tall or short

20. Probability & Heredity
Probability- a number that describes how likely it is that an event will occur
Laws of probability predict what is, and is not, likely to happen
Every time two parents produce offspring, the probability if certain traits getting passed on is the same
To determine the probability of inheriting alleles, geneticists use Punnett squares

21. Punnett Squares
Used to determine the probability of inheriting certain alleles
Prior to constructing/using a Punnett square you need to know:
The traits being considered
Whether the parents are purebred or hybrid
Example: cross between two pea plants that are both hybrid for height (Tt)

22. Constructing a Punnett Square Cross between two pea plants that are both hybrid for height (Tt)
Draw a square box divided into four square parts
Determine the alleles of each parent, then place one set of alleles on the top of the columns of the box and the other next to the rows
Do the cross by combining the letter at the top of each column with the letter of the row the box is in (Always write a dominant allele before a recessive one)
Determine the likelihood of the different combinations of alleles
Determine which trait is expressed for each combination of alleles

23. Using a Punnett Square
Cross between a purebred tall pea plant with a purebred short pea plant
Cross between a hybrid tall pea plant with a purebred short pea plant

24. Genes and the Environment
A combination of inherited traits and acquired traits help many organisms survive in their environments.
Inherited traits are features or characteristics that result from genes passed from parents to offspring
Acquired traits are physical characteristics or behaviors that are not genetically passed down to an offspring
Are the result of learned behaviors and by an organisms interactions with its environment

25. Environmental Influence
Organisms interact with their environments on a regular basis
Some of these interactions may change the way a gene is expressed (how the inherited traits appear)
The environment can lead to several changes in the way genes are expressed
Changes in the way certain genes behave
May alter the way an organism functions, producing traits that would not normally have been expressed
Theses changes may cause cancer or diseases
Not all changes in genes caused by environmental factors get passed to offspring
In order to pass on gene that were change by the environment, the change must occur in one of the sex cells (egg or sperm)