1. Practice your genetics vocabulary
Genetics Unit Review
Practice your genetics vocabulary

2. Gene A section of DNA that determines a trait OR…
A set of instructions in the DNA to make a protein

3. Allele
A form of a gene

4. Dominant allele The strong form of a gene
When it is present, it hides the weaker allele

5. Recessive allele
The weaker form of a gene

6. Phenotype The physical trait that an organism shows
Examples: Tall, short or Curly hair

7. Genotype The 2 alleles that an organism has for a trait
Examples: TT, Tt or tt

8. Incomplete Dominance
When there are 2 alleles for a trait but neither completely hides the other
There are 3 phenotypes
Example: Hair texture: CC=curly, SS=straight, CS=wavy

9. Purebred When an organism has 2 of the same alleles for a trait
Examples: TT or tt

10. Hybrid When an organism has 2 different alleles for a trait
Example: Tt

11. Gametes
Special cells that contain half the total number of chromosomes
Also know as?
sex cells, sperm or egg cells
What kind of cell division makes gametes?
Meiosis

12. Meiosis
A type of cell division that produces cells with half the normal number of chromosomes
Makes gametes
How does meiosis help to create variety in offspring?
Meiosis shuffles the chromosomes and creates different types of gametes. These different gametes will form offspring that are different from either parent.

13. Fertilization When the sperm and egg combine to form a new organism
What is this first cell called?
A Zygote
What type of reproduction is this a part of?
Sexual Reproduction

14. Sexual Reproduction A type of reproduction that requires 2 parents
It produces offspring that are different from their parents and siblings.
Examples: Mammals, flower producing plants

15. Asexual Reproduction
A type of reproduction that requires only 1 parent
It produces offspring that are identical to the parent.
Example: Amoeba reproduce this way

16. Chromosome A tightly wound section of DNA that contains many genes
How many chromosomes do humans have in each body cell?
46 or 23 pairs

17. What is this diagram showing you?
DNA is stored in the nucleus
A chromosome is made up of tightly wound DNA

18. Sex Chromosomes Humans have 2 chromosomes that determine sex
X and Y chromosomes
A person with XX is a?
girl
A person with XY is a?
boy

19. Genetic Disorders
What is an example of a genetic disorder that is caused by a dominant allele?
Achondroplasia (form of dwarfism), polydactylism (more than 5 fingers)
What is an example of a genetic disorder that is caused by a recessive allele?
Phenyketonuria (PKU), Albinism, Sickle-cell anemia
What is an example of a genetic disorder that is caused by a change in the number of chromosomes?
Down Syndrome, Klinefelter and Turner Syndromes

20. Genetic Disorders What is a carrier?
A person who has the allele for a disorder but who does not show the disorder
Why can’t there be “carriers” for dominant allele disorders?
A person cannot have a dominant allele and not show it. If the person has the dominant allele, they have the disorder.

21. Sex-linked Traits
A trait whose gene is on the sex chromosomes, usually the X
Examples: colorblindness, hemophilia
Why are men more likely to have a sex-linked disorder?
They only have 1 X chromosome so they do not have a backup copy if they get an allele that causes a disorder on their X chromosome

22. DNA Nucleotide A building block of DNA It’s common parts are:
a sugar, a phosphate and a nitrogen base
The 4 nitrogen bases are:
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
Which bases always pair up?
A with T, C with G

23. DNA sequence DNA codes for proteins in the order of the? bases
Here is one side of a DNA molecule: A T C G G G C T T
What is the order of the bases on the other side of the DNA?
T A G C C C G A A
How many bases does that DNA sequence code for? 3

24. DNA Replication The process by which DNA copies itself
What are the steps?
1) DNA unzips
2) Nucleotides then attach to each single strand
3) 2 identical strands are then formed

25. Protein Synthesis The process by which proteins are made
What are the steps?
1) DNA must be transcribed into mRNA
2) mRNA is then read by a ribosome
3) Ribosomes translate the mRNA instructions into a chain of amino acids (protein)

26. Mutation
A change in the DNA sequence which can change the protein that is made from the DNA instructions
Give an example of a helpful mutation:
6th finger in pandas
Give an example of a harmful mutation:
hemophilia
Give an example of a neutral mutation:
blue eyes
Give an example of a mutation that is both helpful and harmful:
sickle cell anemia

27. Mutagen Substance or condition that can cause mutations
Exposure to mutagens can cause cancer
Examples?
X-rays
UV rays from sunlight
Radiation
Chemicals in pesticides and cigarette smoke