2. Transcription , Translation, Inheritance, Advanced Punnett Square

What are genes made of?

Genes are made of DNA and serve as the blueprint for traits such as height, hair color, and eye color.

What are the two levels of gene expression?

transcription and translation

What is the Central Dogma of Biology?

DNA → RNA → Protein, involving replication, transcription, and translation.

What happens during replication?

DNA is copied to produce more DNA.

How is RNA produced in transcription?

DNA is converted to RNA, similar to extracting a specific recipe from a cookbook.

What happens during translation?

RNA is converted into proteins, similar to following a recipe to create a dish.

What does mRNA do?

mRNA carries the genetic instructions for protein synthesis.

Where does transcription occur in eukaryotes and prokaryotes?

In eukaryotes, transcription occurs in the nucleus. In prokaryotes, transcription occurs in the cytoplasm.

What are the three phases of bacterial transcription?

Initiation, elongation, and termination.

What happens in the elongation phase of bacterial transcription?

RNA polymerase moves along the DNA template, synthesizing RNA.

What is the role of the sigma factor in bacterial transcription?

The sigma factor binds to RNA polymerase and the DNA promoter, guiding RNA polymerase to the correct starting point.

What do DNA instructions lead to the formation of?

Polypeptides, which fold into functional proteins.

Genetic code

A series of triplets (codons) where each codon corresponds to a specific amino acid.

What is the function of the start codon "AUG"?

"AUG" signals the beginning of protein synthesis.

What are the stop codons, and what is their role?

"UAA," "UAG," and "UGA" are stop codons, signaling the end of translation.

How can mutations affect translation?

Mutations can shift the reading frame, altering the amino acid sequence and potentially causing harmful effects.

What is the role of mRNA?

mRNA carries genetic information from DNA to the ribosome and contains codons that determine the amino acid sequence of a protein.

What is tRNA's function in translation?

tRNA carries specific amino acids to the ribosome and has an anticodon complementary to the mRNA codon.

What role does rRNA play in translation?

rRNA is part of the ribosome, facilitating mRNA-tRNA interaction and assembling amino acids into a polypeptide chain.

What are the three stages of translation?

Initiation, elongation, and termination.

What happens during initiation in translation?

The mRNA, tRNA, and ribosome assemble to begin protein synthesis.

What occurs during elongation in translation?

The ribosome moves along the mRNA, adding amino acids based on the codons.

Phenotype

Observable traits (e.g., flower color, height).

Genotype

The genetic makeup determining those traits (e.g., alleles like Tt or tt).

Dominant Traits

Expressed with at least one dominant allele (e.g., T for tall).

Recessive Traits

Only expressed when both alleles are recessive (e.g., tt for short).

What are alleles?

Variants of a gene, represented by letters (e.g., T for tall, t for short), with one allele inherited from each parent.

Homozygous

Two identical alleles (e.g., TT or tt).

Heterozygous

Two different alleles (e.g., Tt).

Incomplete dominance

When neither allele is fully dominant, resulting in an intermediate phenotype.

Codominance

Occurs when both alleles are expressed equally in the phenotype.

What is autosomal recessive inheritance?

A trait is expressed only when an individual inherits two recessive alleles, one from each parent (e.g., sickle cell disease).

What are X-linked genes?

Genes located on the X chromosome. X-linked disorders are more common in males because they only have one X chromosome.