2. Warm-Up
Answer the following questions IN COMPLETE SENTENCES!
What are traits?
What are genes?
Where are genes found?
What are offspring?
How do parents pass down there genetic information to their offspring?

3. Journal Warm up When a person is an 'albino',
Essential Question: How do children inherit traits from their parents?
Journal Warm up
When a person is an 'albino',
they have very pale (almost white)
skin, hair, and eye color. Yet, skin color,
eye color, and hair color are controlled
by 3 different genes. How do you think
a single mutation in a person can cause
all three of these traits to be affected?

4. Essential Question: How do children inherit traits from their parents?
The Basics of Genetics
Principles of Genetics

5. 1. Traits are passed or inherited from one generation to the next.
Essential Question: How do children inherit traits from their parents?
1. Traits are passed or inherited from one generation to the next.

6. What part of your cells contain your genetic instructions?
Essential Question: How do children inherit traits from their parents?
What part of your cells contain your genetic instructions?
Your genetic instructions are located in the nucleus of every cell, stored within chromosomes.

7. How will your traits be passed on to your future children?
Essential Question: How do children inherit traits from their parents?
How will your traits be passed on to your future children?
Fathers pass genetic instructions to offspring through sperm cells.
Mothers pass genetic instructions to offspring through egg cells.

8. Chromosomes: How many? Where are they?
Essential Question: How do children inherit traits from their parents?
Chromosomes: How many? Where are they?
A human body cell contains 46 Chromosomes, which are stored inside every cell’s nucleus.
Human sex cells (sperm or egg) contain 23 chromosomes each.

9. 2. Traits of an organism are controlled by genes.
Essential Question: How do children inherit traits from their parents?
2. Traits of an organism are controlled by genes.
A gene is a section of a chromosome, that codes for a specific trait.
Chromosomes are made of tightly wound strands of DNA and proteins.
gene

10. 3. Organisms inherit genes in pairs, one from each parent.
Essential Question: How do children inherit traits from their parents?
3. Organisms inherit genes in pairs, one from each parent.
Human sex cells (sperm or egg) contain chromosomes each.
When the egg is fertilized, the new baby will have chromosomes in each of its cells, which is the correct number of chromosomes for a human.

11. Sexual Reproduction (2 parents) creates unique offspring.
Essential Question: How do children inherit traits from their parents?
Sexual Reproduction (2 parents) creates unique offspring.
In plants, male chromosomes are passed through pollen grains to female egg cells. Once fertilized, these eggs will develop into seeds.
The new plants will receive a combination of traits from both parents.

12. 4. Some genes are dominant, while others are recessive.
Essential Question: How do children inherit traits from their parents?
4. Some genes are dominant, while others are recessive.
“Stronger” traits are called dominant.
“Weaker” traits are called recessive.
Geneticists use symbols (letters) to represent the different forms of a gene.

13. Dominant traits are represented by a capital letter.
Essential Question: How do children inherit traits from their parents?
Dominant traits are represented by a capital letter.
Yellow seeds are dominant…….. Y

14. Essential Question: How do children inherit traits from their parents?
Recessive genes (for the same trait) are represented by THE SAME lower case letter.
Green seeds are recessive………. y
Dominant (yellow) = Y
Recessive (green) = y

15. Essential Question: How do children inherit traits from their parents?
In pea plants, tall is dominant over short. The letter used to represent the tall gene is T.
The short gene is represented by t.
Tall =T
Short = t

16. In humans, brown eyes are dominant over blue.
Essential Question: How do children inherit traits from their parents?
In humans, brown eyes are dominant over blue.
Brown = B
Blue = b

17. Essential Question: How do children inherit traits from their parents?
5. Dominant genes hide recessive genes when both are inherited by an organism.
Y + y = yellow seeds (yellow is dominant)
T + t = tall plant (tall is dominant)
B+ b = brown eyes (brown is dominant)

18. A PUREBRED organism has two of the same genes for a trait.
Essential Question: How do children inherit traits from their parents?
A PUREBRED organism has two of the same genes for a trait.
TT = purebred TALL
tt = purebred SHORT

19. A HYBRID organism has two different genes for a trait.
Essential Question: How do children inherit traits from their parents?
A HYBRID organism has two different genes for a trait.
Bb = hybrid for black feathers (black is dominant.)
Tt = hybrid TALL (tall is dominant.)

20. Will a hybrid human with the genes Bb have brown or blue eyes?
Bb = Brown eyes
The dominant gene (brown), will be expressed in a hybrid.

21. Why must all blue eyed people be PUREBRED for that trait?
Essential Question: How do children inherit traits from their parents?
Why must all blue eyed people be PUREBRED for that trait?
If the dominant gene is present, it will always be expressed.
The only possible gene combination for blue eyes is bb.

22. 6. Some genes are neither dominant nor recessive
6. Some genes are neither dominant nor recessive. These genes show incomplete dominance.
If an organism shows INCOMPLETE DOMINANCE for a trait, the hybrid will show a blend of the two traits.
In humans, hair texture is such a trait.
Because neither curly or straight hair is recessive, no lower case letters are used.
CC = curly hair
CS = wavy hair
SS = straight hair

23. Essential Question: How do children inherit traits from their parents?
These basic laws of inheritance control the traits of all living organisms on Earth.