Biology Chapter 15: Chromosomal Inheritance

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Questions and Answers

What are the two parts of telomerase?

RNA part and Protein part (correct)

Protein part and Lipid part

DNA part and Protein part

RNA part and DNA part

What role does the RNA part of telomerase serve?

It initiates DNA replication

It signals DNA ligase activity

It removes unnecessary nucleotides

It provides the template for nucleotide placement (correct)

What would happen to a cell lacking telomerase?

It would lose the ability to form RNA primers

It would replicate faster

It would eventually not survive as telomeres shorten (correct)

It would increase the length of the telomeres

How does DNA ligase function in the context of telomerase activity?

It glues the fragments of DNA together Signup and view all the answers

What is the purpose of the RNA primer in DNA replication?

To serve as a template for DNA synthesis Signup and view all the answers

What would occur if exonucleases remove RNA nucleotides during the replication process?

It could lead to incomplete DNA strands Signup and view all the answers

Which strand experiences DNA overhang during replication?

Lagging strand only Signup and view all the answers

What type of enzyme is DNA polymerase HI in the context of telomerase?

It replaces RNA primers with DNA Signup and view all the answers

What role does DNA polymerase play in the proofreading process?

It replaces incorrect nucleotides with correct ones. Signup and view all the answers

What occurs during a mismatch repair scenario?

Enzymes remove the mismatched strand and replace it. Signup and view all the answers

What is the consequence of having mismatched nucleotide pairs such as T with G or A with C?

They create points of instability in the DNA sequence. Signup and view all the answers

Which enzyme is responsible for sealing gaps by joining DNA strands?

Ligase Signup and view all the answers

What is the function of nucleases in the DNA repair process?

To remove mismatched nucleotides. Signup and view all the answers

How does ligase contribute to DNA replication?

It connects Okazaki fragments on the lagging strand. Signup and view all the answers

Which factor can cause DNA overhangs during replication?

Incompletion of the lagging strand synthesis. Signup and view all the answers

What is the main role of RNA primers in DNA replication?

To provide a starting point for DNA synthesis. Signup and view all the answers

What is the function of Single Strand Binding Protein (SSBP) during DNA replication?

To prevent hydrogen bonds from reforming Signup and view all the answers

Which of the following accurately describes the role of primase in DNA replication?

It synthesizes a short RNA primer for DNA polymerase Signup and view all the answers

Why does primase use uracil instead of thymine in RNA synthesis?

Uracil enhances the speed of synthesis Signup and view all the answers

What is the primary role of DNA polymerase in DNA replication?

To create a new DNA strand by adding matching base pairs Signup and view all the answers

What does exonuclease activity in DNA polymerase do?

It cleaves nucleotides from the end of the DNA strand for proofreading Signup and view all the answers

What is a characteristic feature of the lagging strand during DNA replication?

It requires multiple RNA primers Signup and view all the answers

Which statement about telomerase function is true?

It lengthens telomeres at the ends of chromosomes Signup and view all the answers

What is a DNA overhang and where is it commonly found?

A section of single-stranded DNA at the end of a chromosome Signup and view all the answers

Study Notes

Chapter 15: The Chromosomal Basis of Inheritance

DNA is the genetic material, a polymer of nucleotides
Each DNA consists of sugar (deoxyribose), phosphate, and nitrogenous bases (A, T, G, C)
Genes are DNA segments coding for molecules (proteins). These are responsible for phenotypic traits.
Traits are passed to offspring through genes
Chromosomes are long strands of DNA, wrapped around histones, containing thousands of genes.
Chromosome 23 determines sex (XX=female, XY=male)
X and Y chromosomes have different lengths, number, and kinds of protein-coding genes
Phenotypes can be wild type (common) or mutant (changes from wild type due to a mutation or change of allele).
Sex-linked genes are unique to either the X or Y chromosome.
X-linked genes are common in females, while Y-linked genes are usually passed from father to son since there are fewer genes on the Y chromosome.
Genetic disorders can result from chromosomal abnormalities (e.g., Down syndrome, Turner syndrome).
X-inactivation in female mammals silences one X chromosome to avoid producing twice the amount of proteins.
Linked genes tend to inherit together due to a close proximity on a chromosome.
Crossing over during meiosis promotes genetic recombination, which affects inheritance patterns.

Chapter 16: Molecular Basis of Inheritance

DNA is the genetic material, a polymer of nucleotides
DNA has a sugar-phosphate backbone with nitrogenous base pairs (A with T, and C with G).
The base pairs are held together by hydrogen bonds. DNA strands run in opposite directions (anti-parallel).
Chargaff's Rule: DNA base ratios vary across species with the same number of bases.
DNA replication occurs during the S phase of interphase.
DNA replication starts at replication forks, where the helix splits
Enzymes like helicase unwind the DNA, topoisomerase reduces tension, and single-strand binding proteins prevent strand rejoining
DNA polymerase III synthesizes DNA in the 5' to 3' direction, creating leading and lagging strands. Okazaki fragments make up the lagging strand
DNA Polymerase I removes RNA primers and replaces them with DNA.
DNA ligase seals the fragments of DNA.
DNA replication is semi-conservative, where each new DNA molecule has one original strand and one new strand.
DNA proofreading and repair mechanisms correct errors during replication.

Chapter 17: Gene Expression: From Gene to Protein

Gene expression is converting DNA information into protein synthesis, using two steps:
Transcription and translation
Transcription: Converting DNA into mRNA, occurs in the nucleus in eukaryotic cells and the cytoplasm in prokaryotic cells.
- Uses RNA Polymerase to produce a pre-mRNA which is processed to mature mRNA.
- The promoter region with a TATA box guides factors to place themselves before RNA polymerase takes place.
- RNA Polymerase II unwinds the DNA to initiate the transcription.
- Proceeds in the 5' to 3' direction continuously.
- A sequence called the Polyadenylation signal (CAAAUAAA) in the pre-mRNA signals termination.
- Final product includes a 5' cap and 3' poly-A tail to help with stability.
Translation: Converting mRNA into a polypeptide chain. This occurs in the cytoplasm (ribosomes).
mRNA is read by ribosomes in triplets of nucleotides (codons).
- Each codon specifies a particular amino acid.
- tRNA molecules carry specific amino acids to the ribosome based on the mRNA codons' anticodons.
- A peptide bond forms between amino acids as the ribosome moves along the mRNA.
- Codons (UAA, UAG, UGA) signal the end of the polypeptide and release factor detaches.
Post-Translational modifications help to finish the protein folding and structure.
Polyribosomes allow for multiple ribosomes to translate the same mRNA at the same time.

Chapter 22: Descent with Modification: A Darwinian View of Life

Evolution is a process of genetic change in organisms over time.
- Natural selection is a mechanism for evolution in which individuals with traits better suited to their environment are more likely to survive and reproduce. This helps to increase fitness.
- Adaptation is a trait that increases an organism's fitness in its environment.
Evidence for Evolution:
- Direct observations (soapberry bug beak length changes, drug-resistant bacteria)
- Homology (similarities in anatomical structures and development suggesting common ancestry). Vestigial structures are leftovers from previous functions
- Fossil records (transition fossils show intermediate forms of evolution). The fossil record is a chronological record.
- Biogeography (the geographic distribution of species). Species are found in areas in which their ancestors were before geographic events.
Artificial Selection is where humans select and breed specific traits in plants or animals.
Phylogenetic Trees show evolutionary relationships between organisms, representing common ancestors and branching patterns. Nodes represent an unknown common ancestor for two lineages.

Additional Information (General)

Mutations: Changes in DNA sequences. They can be beneficial (supporting adaptation), neutral, or harmful.
Point mutations are changes in a few nucleotides within a DNA sequence. If they happen in a gamete, future generations may be impacted. This may lead to genetic disorders.
Different types of mutations include nucleotide pair substitution (silent, missense, nonsense), insertions, and deletions. These can cause frameshifts resulting in an entire shift of where the codons are read.

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Description

Explore the chromosomal basis of inheritance in this quiz covering Chapter 15. Understand how DNA, genes, and chromosomes relate to phenotypic traits and the inheritance patterns linked to sex chromosomes. Test your knowledge on genetic disorders and sex-linked traits.