Heredity (short answers)

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Questions and Answers

Describe the role of DNA ligase in DNA replication. What would be the immediate consequence if DNA ligase were non-functional?

DNA ligase joins Okazaki fragments on the lagging strand. Without it, Okazaki fragments would not be connected, resulting in fragmented DNA.

Outline the steps of PCR, including the temperatures used and the purpose of each step.

Denaturation (95°C): Separates DNA strands. Annealing (50-65°C): Primers bind to target DNA. Elongation (72°C): DNA polymerase extends primers to replicate DNA.

Explain how non-disjunction in meiosis can lead to genetic disorders such as Down syndrome.

Non-disjunction is the failure of homologous chromosomes or sister chromatids to separate during meiosis, resulting in gametes with an abnormal number of chromosomes. If a gamete with an extra chromosome 21 fertilizes a normal gamete, the resulting zygote will have trisomy 21, leading to Down syndrome.

Contrast the processes of mitosis and meiosis, highlighting key differences in their purpose and outcomes.

Mitosis produces two identical diploid daughter cells for growth and repair, while meiosis produces four genetically different haploid gametes for sexual reproduction. Signup and view all the answers

Describe the role of telomeres and telomerase in maintaining the integrity of chromosomes during DNA replication.

Telomeres are repetitive DNA sequences at the ends of chromosomes that protect against DNA degradation and fusion with neighboring chromosomes. Telomerase is an enzyme that lengthens telomeres, preventing the progressive shortening of DNA during replication. Signup and view all the answers

Explain how gel electrophoresis is used to separate DNA fragments and how the results can be interpreted.

Gel electrophoresis separates DNA fragments by size. Smaller fragments migrate faster and further through the gel. The resulting banding pattern can be used to determine the size of DNA fragments and compare DNA samples. Signup and view all the answers

Outline the process of binary fission in bacteria and how it compares to mitosis in eukaryotes.

Binary fission is a simpler process where the bacterial chromosome replicates and the cell divides into two identical daughter cells. Unlike mitosis, it does not involve the formation of a spindle apparatus or nuclear envelope breakdown. Signup and view all the answers

Describe the process of crossing over during meiosis and explain its significance in generating genetic diversity.

Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis. This results in new combinations of alleles on each chromosome, increasing genetic variation in the resulting gametes. Signup and view all the answers

Explain the concepts of incomplete dominance and co-dominance. Give a specific example of each.

Incomplete dominance results in a blended phenotype where neither allele is fully dominant (e.g., a pink flower from red and white parents). Co-dominance results in both alleles being expressed simultaneously (e.g., AB blood type). Signup and view all the answers

Describe the role of restriction enzymes in biotechnology and explain how they are used to create recombinant DNA.

Restriction enzymes cut DNA at specific recognition sites, creating fragments with sticky or blunt ends. These fragments can be joined with other DNA fragments using DNA ligase to create recombinant DNA. Signup and view all the answers

Define the term 'gene linkage' and explain how linked genes affect inheritance patterns compared to unlinked genes.

Gene linkage refers to genes located close together on the same chromosome that tend to be inherited together. Linked genes do not assort independently, affecting phenotypic ratios compared to unlinked genes. Signup and view all the answers

Explain the difference between a genotype and a phenotype. How can the same genotype result in different phenotypes?

Genotype is the genetic makeup of an organism, while phenotype is the observable characteristics. The same genotype can result in different phenotypes due to environmental factors or epigenetic modifications. Signup and view all the answers

What is the role of the promoter region in gene expression? What would happen if a mutation occurred in the promoter region of a gene?

The promoter region is a DNA sequence where RNA polymerase binds to initiate transcription. A mutation in the promoter region can alter or prevent RNA polymerase binding, affecting gene expression levels. Signup and view all the answers

Briefly explain the process of Sanger sequencing and its importance in determining the nucleotide sequence of DNA.

Sanger sequencing involves DNA synthesis with chain-terminating dideoxynucleotides. This produces fragments of varying lengths, which are then separated by size to determine the DNA sequence. Signup and view all the answers

Describe the concept of epigenetic inheritance and how it can influence phenotypes across generations without changes in the DNA sequence.

Epigenetic inheritance involves modifications to DNA or histone proteins that alter gene expression without changing the underlying DNA sequence. These modifications can be passed on to future generations, influencing their phenotypes. Signup and view all the answers

Explain how the CRISPR-Cas9 system works for gene editing. What are the main components and how do they function together?

CRISPR-Cas9 uses a guide RNA to direct the Cas9 enzyme to a specific DNA sequence, where Cas9 cuts the DNA. The cell's repair mechanisms then either disrupt the gene or insert a desired sequence. Signup and view all the answers

Distinguish between autosomes and sex chromosomes. What is the typical human chromosome arrangement for each sex?

Autosomes are non-sex chromosomes (22 pairs in humans), while sex chromosomes determine sex (one pair: XX for females, XY for males). Signup and view all the answers

Describe how a frameshift mutation occurs and explain its potential impact on the resulting protein.

A frameshift mutation is an insertion or deletion of nucleotides that is not a multiple of three, altering the reading frame of the mRNA during translation. This can lead to a completely different amino acid sequence and a non-functional protein. Signup and view all the answers

Explain the concept of independent assortment and its role in generating genetic variation during meiosis.

Independent assortment states that alleles of different genes assort independently of one another during gamete formation. This means that the inheritance of one gene does not affect the inheritance of another, leading to new combinations of alleles in the gametes. Signup and view all the answers

What role do checkpoints play in the cell cycle and what might be the consequence if a checkpoint fails?

Checkpoints monitor the cell cycle for errors and halt progression until corrected. If a checkpoint fails, cells with damaged DNA may continue to divide, potentially leading to mutations or cancer. Signup and view all the answers

Flashcards

DNA Replication

The process by which DNA is duplicated.

Cell Division

The process by which a cell divides to produce two daughter cells.

Inheritance

The passing on of traits from parents to offspring.

Gene Linkage

Genes located on the same chromosome that tend to be inherited together.

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Biotechnology

The use of living systems and organisms to develop or make products.