biology - DNA replication + inheritance SL

What is the specific role of Helicase?

It separates the DNA strands by breaking the hydrogen bonds between the complementary base pairs.

What chemical bonds does DNA Polymerase form?

It forms covalent bonds between phosphate groups to create the continuous sugar-phosphate backbone.

What is the "Primer" and what enzyme makes it?

A primer is a short starter sequence necessary because DNA polymerase cannot start from nothing. It is synthesized by the enzyme Primase.

What is the leading strand?

Synthesized continuously towards the replication fork.

What is the lagging strand?

Synthesized discontinuously away from the replication fork.

What are Okazaki Fragments?

These are the short, separate fragments of DNA synthesized on the lagging strand.

What is the function of DNA Ligase?

It acts as a "glue" to join the Okazaki fragments together. It specifically seals the "nicks" in the sugar-phosphate backbone.

How does DNA Polymerase ensure accuracy (Proofreading)?

DNA polymerase "proofreads" the chain. If it detects an incorrect base pair (e.g., A-C instead of A-T) , it removes the incorrect base and replaces it with the correct one.

What happens to the RNA primers after replication?

DNA Polymerase I removes the RNA primers and replaces them with DNA nucleotides.

What is the direction of DNA synthesis?

DNA polymerase adds nucleotides in the 5' to 3' direction.

What is a "Nuclease"?

It is an enzyme involved in repair that can cut out damaged or mismatched DNA segments (excision) so they can be replaced.

What is the "Denaturation" step in PCR?

The sample is heated to separate the double-stranded DNA into single strands. This breaks the hydrogen bonds.

What is the "Annealing" step in PCR?

The temperature is lowered (cooled) to allow primers to bind (anneal) to their specific complementary sequences on the target DNA.

What is the "Extension" step in PCR?

The temperature is raised again so Taq Polymerase can extend the new DNA strands from the primers.

Why is "Taq Polymerase" used specifically?

It is a heat-stable polymerase that can withstand the high temperatures required for PCR without denaturing.

What are STRs (Short Tandem Repeats)?

These are specific regions in DNA that contain short, repeated sequences. The number of repeats varies greatly between individuals , making them unique "genetic fingerprints".It is a heat-stable polymerase that can withstand the high temperatures required for PCR without denaturing.

What are the practical applications of DNA profiling?

Forensics (identifying suspects from blood/hair), Paternity testing, and Environmental monitoring.

What was the first step in Mendel's cross-pollination?

He selected parent plants and removed the anthers (male parts) from the female parent.

Why did Mendel remove the anthers?

To prevent self-pollination and ensure the offspring were the result of the specific cross he intended.

How did Mendel fertilize the plants?

He manually transferred pollen from the anthers of the male parent to the female parent.

What is the P generation?

The original parental generation

What is the F1 generation?

The "First Filial" generation; offspring of the P cross

What is the F2 generation?

The "Second Filial" generation, produced by self-pollinating the F1 plants

What is Phenotypic Plasticity?

The ability of one genotype to produce different phenotypes depending on environmental conditions. It highlights the interaction between genes and environment.

What is Incomplete Dominance?

A pattern where neither allele is fully dominant. The heterozygote phenotype is an intermediate blend of the two parents (e.g., Red + White = Pink).

What is Klinefelter's Syndrome?

A chromosomal disorder in males with an extra X chromosome (XXY). It causes reduced fertility and underdeveloped reproductive organs.

What is Turner's Syndrome?

A chromosomal disorder in females with a missing X chromosome (XO).

Why is Hemophilia more common in males?

It is an X-linked recessive disorder. Males (XY) have only one X chromosome, so a single defective gene causes the disease. Females (XX) have a second X that can provide a functional gene, making them "carriers".

What is the Law of Segregation?

Alleles for a specific gene separate (segregate) from each other during gamete formation (meiosis).

What is the Law of Independent Assortment?

Genes for different traits segregate independently of one another during gamete formation.

How does Gel Electrophoresis separate DNA?

It separates DNA fragments based on size. An electric current pulls the DNA through a gel; smaller fragments move faster and further than larger ones.