Lesson 1
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a. What does DNA carry?
DNA carries the genetic instructions used in the growth, development, functioning, and reproduction of all known living organisms and many viruses.b. What is the shape?
The shape of DNA is a double helix. -
What base pairs are found in DNA and how are they paired? What is the different base that RNA has, and what does it pair with?
The base pairs found in DNA are adenine (A) paired with thymine (T), and cytosine (C) paired with guanine (G). In RNA, the base uracil (U) replaces thymine (T) and pairs with adenine (A).
Lesson 2
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Describe a chromosome.
A chromosome is a long, thread-like structure composed of DNA and proteins. It carries genetic information in the form of genes and is found in the nucleus of eukaryotic cells. Each species has a specific number of chromosomes. -
What types of cells undergo meiosis, and what is produced during meiosis?
Meiosis occurs in germ cells (gametes) to produce sex cells: sperm in males and ova in females. It results in four non-identical haploid cells, each with half the number of chromosomes of the original cell. -
What is crossing over, and in what phase of meiosis does it occur?
Crossing over is the exchange of genetic material between homologous chromosomes during meiosis. It occurs during prophase I of meiosis. -
Describe the Law of Independent Assortment.
The Law of Independent Assortment states that alleles for different traits are distributed to gametes independently of one another. This means that the inheritance of one trait generally does not influence the inheritance of another trait.
Lesson 3
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What are amino acids?
Amino acids are organic compounds that serve as the building blocks of proteins. They are made up of an amino group, a carboxyl group, and a unique side chain.a. How many are there?
There are 20 standard amino acids.b. What is a codon?
A codon is a sequence of three nucleotides in mRNA that encodes a specific amino acid or signals the termination of a protein synthesis.
Lesson 4
- What are environmental factors and how does it relate to genetics?
Environmental factors are external influences that can affect the expression of genes and traits in an organism. They can include things like nutrition, temperature, and exposure to toxins. These factors can influence how genes are expressed, leading to variations in phenotype.
Lesson 5
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Summarize the types of mutations.
- Substitution: A single nucleotide is replaced by another nucleotide. It may lead to a single amino acid change in a protein (missense) or have no effect (silent).
- Insertion: One or more nucleotides are added into the DNA sequence, which can disrupt the reading frame.
- Frameshift: Occurs when there is an insertion or deletion of nucleotides that changes the reading frame of the gene, which typically leads to a completely different protein being produced.
- Deletion: One or more nucleotides are removed from the DNA sequence, potentially leading to a loss of function.
- Viable error: A mutation that does not result in detrimental effects on the organism's survival; it could lead to variation without affecting health or fitness.
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What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes that are similar in shape, size, and genetic content. One chromosome of each pair is inherited from each parent.
Lesson 6
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What are somatic cells? What happens if there is a mutation in a somatic cell?
Somatic cells are any cells in the body that are not sperm or egg cells. If a mutation occurs in a somatic cell, it can lead to cancer or other diseases but is not passed on to the next generation. -
Why does color blindness affect males more than females?
Color blindness is often linked to X-linked recessive genes. Males have one X and one Y chromosome (XY), while females have two X chromosomes (XX). If a male inherits the mutated gene on his X chromosome, he will express color blindness, while a female would need to inherit the mutated gene on both X chromosomes to express the trait, making it less common in females.
Lesson 7
- Are all mutations a bad thing? Explain.
No, not all mutations are bad. Some mutations can be neutral or even beneficial, leading to variation that can affect an organism's adaptability, evolution, and survival. They can contribute to diversity in populations and may lead to advantageous traits.
Lesson 9
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What is the difference between genotype and phenotype?
Genotype refers to the genetic makeup of an organism, specifically the alleles it carries (e.g., AA, Aa, aa), while phenotype refers to the observable characteristics or traits of an organism (e.g., eye color, height). -
What is the difference between codominance and incomplete dominance?
In codominance, both alleles in a heterozygous condition are fully expressed, resulting in a phenotype that shows both traits (e.g., AB blood type). In incomplete dominance, the phenotype is a blend of both alleles, creating an intermediate phenotype (e.g., red and white flowers producing pink flowers).
Lesson 10
- How do you know which allele for a trait is dominant?
An allele is considered dominant if its presence masks the expression of another allele in a heterozygous condition, meaning that only one copy of the dominant allele is needed for the trait to be expressed.
Punnett Square Practice
- Complete this Punnett Square. Imagine Brown Eyes (T) are dominant to Blue Eyes (t).
| | T | t | |----|---|---| | T | TT | Tt | | T | TT | Tt |
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What is the percent chance (probability) of genotype TT?
50% -
What is the percent chance (probability) of genotype Tt?
50% -
What is the percent chance (probability) of genotype tt?
0% -
What is the probability of the phenotype of brown eyes?
100% (both TT and Tt generate brown eyes) -
What is the probability of the phenotype of blue eyes?
0% (only tt would generate blue eyes)