1. 4.1 Living Things Inherit Traits in Patterns
We know the offspring produced by sexual reproduction have genetic material from two parents
Offspring get traits from parents
But not all traits

2. 4.1 Living Things Inherit Traits in Patterns
Inherited trait
characteristic passed down from parents
born with it
determined by genes
Acquired Trait
characteristic developed during life

3. 4.1 Living Things Inherit Traits in Patterns
In the table below, write yes if the trait is the result of heredity or no if it is not.
Trait
Result of Heredity?
Blonde hair
Able to speak English
Able to ride a bike
Green eyes
Yes No No
Yes

4. 4.1 Living Things Inherit Traits in Patterns
If a mother works out as a body builder for many years, are the chances high that her offspring will inherit strong muscles? Why or why not?
The offspring has the potential for strong muscles, but a muscle grows if it is worked. The child will have to do the same workouts to get big muscles, he/she will not be born with them.

5. 4.1 Living Things Inherit Traits in Patterns
Inherited traits are controlled or coded for by genes
genes – unit of heredity that codes for a particular trait
examples:
Eye color
Hair color
heredity
Passing of genes from parent to offspring

6. There are various forms of the same gene
4.1 Living Things Inherit Traits in Patterns
There are various forms of the same gene
Example –
Eye color has several variations
brown
blue
green
hazel
These variations are called alleles

7. Example: Brown or blonde hair What is the gene? What is the allele?
4.1 Living Things Inherit Traits in Patterns
Example:
Brown or blonde hair
What is the gene?
What is the allele?

8. 4.1 Living Things Inherit Traits in Patterns
Example:
Brown or blonde hair
When working with heredity, genes are assigned a letter
The gene would code for hair color and could be represented by the letter H
So each allele would be a variation of the letter H to represent a variation of the gene
H = brown
h = blonde

9. 4.1 Living Things Inherit Traits in Patterns
Capital letter represent dominant alleles and lower case letters represent recessive alleles
Dominant – an allele that determines the phenotype of an individual organism when two different copies are present in the genotype
Recessive – an allele that is not expressed when combined with a dominant form of a gene. It is only expressed in the phenotype when both alleles present in the genotype are recessive

10. 4.1 Living Things Inherit Traits in Patterns
If a dominant allele is present, the trait of the dominant allele shows. Whether one or two dominant alleles are present
If there is no dominant allele, and both alleles present are recessive, then the recessive trait shows

11. Dominant traits are expressed even if only one allele codes for it.
4.1 Living Things Inherit Traits in Patterns
Why are some parents’ traits expressed in their offspring while others are not?
Dominant traits are expressed even if only one allele codes for it.
If a trait is recessive, both alleles must be recessive for it to show in the phenotype.

12. Eye color is represented by the letter E
4.1 Living Things Inherit Traits in Patterns
The combination of alleles is the genotype
The trait that shows as a result of the genotype is the phenotype
Example -
Eye color is represented by the letter E
E = brown
e = blue EE Ee ee
Genotypes
The resulting phenotypes
Blue eyes
Brown eyes
Brown eyes

13. 2 recessive alleles = dominant phenotype 2 dominant alleles =
4.1 Living Things Inherit Traits in Patterns
dominant phenotype
2 dominant alleles =
1 dominant allele
and 1 recessive allele =
dominant phenotype
recessive phenotype
2 recessive alleles =

14. 4.1 Living Things Inherit Traits in Patterns
A science student crosses a purebred regular height pea plant with a dwarf height plant. Four new pea plants are grown. Draw the four pea plants in the space below. Be sure to make them the right height.

15. 4.2 Patterns of Heredity can be Predicted
Unit A
Chapter 4

16. Punnett Squares
chart used to show all of the ways genes from two parents can combine and be passed on to offspring
shows possible outcomes for inheritance - the possible combinations of parents alleles
the top part shows one parent’s alleles for a trait HH H h
the side shows the other parent’s alleles for a trait H H H H h h H h h h

17. 1. How is the symbol for each allele the same?
Each allele for a trait is symbolized by the same letter

18. 2. How can you tell which allele is dominant?
Dominant alleles are symbolized by capital letters.

19. 3. How can you tell which allele is recessive?
Recessive alleles are symbolized by lower case letters.

20. 4. Which trait is dominant here?
Regular height (H)

21. 5. Which trait is recessive here?
Dwarf height (h)

22. The alleles of one possible offspring
6. What does each box show?
The alleles of one possible offspring

23. 4.3 Meiosis is a special form of cell division
Sexual reproduction involves two parents
Each parent produces specialized cells that contain half the amount of genetic material a cells needs
The specialized cells contain one allele for each gene and are called haploid cells

24. 4.3 Meiosis is a special form of cell division
Haploid cells
contain half the usual number of chromosomes (one chromosome from each pair of chromosomes)
1n cells
also known as gametes
egg – gamete of the female
sperm – gamete of the male

25. 4.3 Meiosis is a special form of cell division
The cell resulting from a sperm and egg combining has a full set of DNA
They have two alleles per gene and are called diploid cells

26. 4.3 Meiosis is a special form of cell division
Diploid cells
contains the full number of chromosomes (both chromosomes in a pair)
2n cells

27. 4.3 Meiosis is a special form of cell division
Example: In humans
haploid cells have 23 chromosomes
diploid cells have 46 chromosomes

28. 4.3 Meiosis is a special form of cell division
special kind of cell division that produces haploid cells
involves two divisions of a single cell
takes place only in reproductive tissues of an organism
necessary for sexual reproduction

29. 4.3 Meiosis is a special form of cell division
during sexual reproduction, the gametes (1n) combine to become a 2n cell that grows into the offspring:
genetic information from the mother
combines with
genetic information from the father
to form
A new cell
fertilization – sperm and egg combine to form one new cell
the new cell that is formed has half its genetic information from its mother and half from its father

30. Meiosis II
Meiosis I