Genetics II: From Genotype to Phenotype Flashcards

Flashcards covering DNA structure, replication, protein synthesis, mutations, and non-Mendelian genetics based on lecture notes.

What are the four biological roles of genetic material?

1. Accurate replication; 2. Stable structure; 3. Capable of coding for diverse information, including proteins; 4. Capable of transmitting this information to regulate development and normal cell functioning.

What are the three building blocks of a DNA nucleotide?

A Phosphate group, a Sugar (deoxyribose), and a Nitrogenous base.

What are the structural differences between purines and pyrimidines?

Purines have two fused rings, whereas pyrimidines have one single ring.

Which nitrogenous bases are categorized as purines and which are pyrimidines?

Purines include Adenine and Guanine; Pyrimidines include Thymine and Cytosine.

What are Chargaff's Rules regarding DNA base pairing?

$A = T$ and $G = C$.

Who provided the X-ray diffraction photos that served as clues for DNA structure?

Rosalind Franklin.

In what year did James Watson and Francis Crick determine the structure of DNA?

1953.

What are the two primary functions of Deoxyribonucleic Acid (DNA)?

Replication (cell division) and Protein Synthesis (genotype to phenotype).

What process results in two identical copies of a DNA molecule during cell division?

DNA Replication.

Define genotype and phenotype.

Genotype refers to the underlying genes, while phenotype is the physical outcome.

What is a codon?

A sequence of three nucleotide bases which code for one amino acid.

How many different sequences can be produced by four nucleotide bases, and how many amino acids do they specify?

$4 \times 4 \times 4 = 64$ different sequences, which specify 20 amino acids (redundancy).

What is the definition of a gene?

A sequence of DNA bases that carries information for synthesizing a particular protein and occupies a specific chromosomal locus.

What are the structural differences between RNA and DNA?

RNA is single stranded, contains ribose sugar, and uses Uracil base; DNA is double stranded, contains deoxyribose sugar, and uses Thymine base.

What occurs during the Transcription phase of protein synthesis?

Inside the nucleus, DNA splits at the gene region to attract complementary ribonucleotides, and a complementary messenger RNA (mRNA) strand is synthesized.

What is the DNA triplet "AAA CGC" transcribed to in mRNA?

UUU GCC.

What happens during Translation in protein synthesis?

Outside the nucleus at the ribosome, tRNA molecules bind to the mRNA strand, bringing amino acids that bind together to form a protein chain.

What are the four types of DNA mutations listed?

1. Point mutations; 2. Duplication; 3. Inversion; 4. Deletions (frame-shift).

What is a synonymous mutation?

A mutation at the nucleotide base level that results in a change to a functionally equivalent amino acid, and may or may not alter function.

What is the definition of Codominance?

A condition where both alleles in a heterozygous condition are fully expressed, such as in the ABO blood system.

Why are X-linked traits more commonly expressed in males?

Because males ($XY$) have only one X chromosome, any allele on that chromosome will be expressed, whether it is dominant or recessive.

What is the difference between polygenic traits and pleiotropy?

Polygenic traits are influenced by two or more genes (continuous variation like stature), while pleiotropy is when a single gene influences multiple traits simultaneously (e.g., Marfan syndrome).

What percentage of DNA similarity is shared between humans and chimpanzees?

$99\%$ similarity.

What is the difference between introns and exons?

Exons are DNA segments that are transcribed and joined together (spliced) to form mRNA, while introns are non-protein coding regions that are eliminated.