Honors Biology Final 24-25

Meiosis

A type of cell division that reduces the chromosome number by half, resulting in the production of four genetically diverse daughter cells.

Difference between meiosis and mitosis

Meiosis involves two rounds of cell division and produces four non-identical daughter cells, while mitosis involves one round of cell division and produces two identical daughter cells.

Type of cells where meiosis occurs

Meiosis occurs in germ cells, which are involved in the production of gametes (sperm and eggs).

Total cell divisions in meiosis

There are two total cell divisions in meiosis: Meiosis I and Meiosis II.

Final number of daughter cells produced by meiosis

Meiosis produces four daughter cells.

Genetic identity of daughter cells in meiosis

The daughter cells produced in meiosis are genetically different due to the processes of crossing over and independent assortment.

Chromosome number in meiosis 2 compared to parent cell

The chromosome number in cells produced by meiosis II is half the number of chromosomes in the original parent cell.

Homologous chromosomes

Chromosomes that are similar in shape, size, and genetic content, with one inherited from each parent.

Purpose of crossing over

Crossing over increases genetic variation by exchanging genetic material between homologous chromosomes during meiosis.

Stage where crossing over occurs

Crossing over occurs during Prophase I of meiosis.

Events during Prophase I

Chromosomes condense, homologous chromosomes pair up, and crossing over occurs.

Key events during Metaphase I

Homologous chromosome pairs align along the metaphase plate.

Separation during Anaphase I

Homologous chromosomes are pulled apart to opposite poles of the cell.

Result of Telophase I

The cell divides into two daughter cells, each with half the number of chromosomes.

Occurrence between Meiosis I and Meiosis II

There is a short interphase where DNA does not replicate.

Events during Prophase II

Chromosomes condense again and the nuclear envelope breaks down if it was reformed.

Alignment during Metaphase II

Chromosomes line up along the metaphase plate.

Separation during Anaphase II

Sister chromatids are pulled apart to opposite poles of the cell.

End result of Telophase II and cytokinesis

Four genetically diverse haploid daughter cells are formed.

Meiosis and genetic diversity

Meiosis contributes to genetic diversity through crossing over and independent assortment.

Independent assortment

The random distribution of homologous chromosomes during meiosis, occurring in Metaphase I.

Role of crossing over in genetic variation

Crossing over creates new combinations of alleles, increasing genetic diversity.

Random fertilization and genetic variation

Random fertilization increases genetic variation by combining different gametes from two parents.

DNA

Deoxyribonucleic acid, the molecule that carries genetic information.

Primary function of DNA

To store and transmit genetic information necessary for the growth, development, and reproduction of organisms.

Location of DNA in eukaryotic cells

DNA is located in the nucleus of eukaryotic cells.

Type of macromolecule DNA is

DNA is a nucleic acid.

Subunits of DNA

DNA is made up of nucleotides.

Scientists who discovered DNA structure

James Watson and Francis Crick are credited with discovering the double helix structure of DNA.

Shape of DNA molecule

The shape of a DNA molecule is a double helix.

Components of a nucleotide

A nucleotide consists of a phosphate group, a sugar (deoxyribose), and a nitrogenous base.

Four nitrogenous bases in DNA

The four nitrogenous bases are adenine (A), thymine (T), cytosine (C), and guanine (G).

Nitrogen bases that pair together

Adenine pairs with thymine (A-T) and cytosine pairs with guanine (C-G).

Bond holding nitrogenous bases together

Hydrogen bonds hold the nitrogenous bases together.

Backbone of the DNA molecule

The sugar and phosphate groups make up the backbone of the DNA molecule.

Rungs of the DNA ladder

The nitrogenous bases form the 'rungs' of the DNA ladder.

Antiparallel DNA strands

Antiparallel means that the two strands of DNA run in opposite directions.

Rule for nitrogenous base pairing

The Chargaff's rule explains how nitrogenous bases pair in DNA.

Complementary strand for ATCG

The complementary strand for ATCG is TAGC.

DNA replication

The process by which DNA makes a copy of itself before cell division.

Importance of DNA replication

DNA replication is important for ensuring that each new cell receives an exact copy of the DNA.

Phase of cell cycle for DNA replication

DNA replication occurs during the S phase of the cell cycle.

Location of DNA replication in the cell

DNA replication takes place in the nucleus.

Semi-conservative DNA replication

Semi-conservative means that each new DNA molecule consists of one original strand and one new strand.

New DNA molecules produced after replication

Two new DNA molecules are produced after replication.

Comparison of new DNA molecules to original

Each new DNA molecule is identical to the original DNA molecule.

Enzyme that unzips DNA

Helicase is the enzyme that unzips the DNA double helix.

Enzyme that builds new DNA strand

DNA polymerase is the enzyme that builds the new DNA strand.

Enzyme joining Okazaki fragments

DNA ligase is the enzyme that joins Okazaki fragments together.

Role of primase in DNA replication

Primase synthesizes a short RNA primer to initiate DNA synthesis.

Function of topoisomerase

Topoisomerase relieves the strain of unwinding the DNA double helix.

First step in DNA replication

The first step in DNA replication is the unwinding of the DNA double helix.

What happens after DNA is unzipped

After the DNA molecule is unzipped, new nucleotides are added to each strand.

Replication fork

A replication fork is the area where the DNA is being unwound and replicated.

Primer and its necessity

A primer is a short RNA sequence necessary for DNA polymerase to start synthesis.

Direction of DNA polymerase synthesis

DNA polymerase synthesizes the new strand in the 5' to 3' direction.

Leading strand

The leading strand is synthesized continuously towards the replication fork.

Lagging strand

The lagging strand is synthesized in short segments away from the replication fork.

Okazaki fragments

Okazaki fragments are short segments of DNA synthesized on the lagging strand.

Difference in synthesis of lagging and leading strands

The lagging strand is synthesized discontinuously in fragments, while the leading strand is synthesized continuously.

What happens after both strands are fully synthesized

After both strands are fully synthesized, the DNA molecule rewinds into a double helix.

What happens after both strands are fully synthesized?

The DNA strands separate, and the process of replication is complete.

What rule governs which bases pair together?

The base pairing rule states that adenine pairs with thymine, and cytosine pairs with guanine.

If a DNA strand has the sequence 5'-ATGCCAT-3', what is the complementary strand?

The complementary strand is 3'-TACGGTA-5'.

How does DNA polymerase ensure accuracy during replication?

DNA polymerase checks the newly added base against the template strand.

What is proofreading in the context of DNA replication?

Proofreading is the process by which DNA polymerase removes incorrectly paired nucleotides.

What happens if an error is not corrected during replication?

An uncorrected error may lead to mutations in the DNA sequence.

What is transcription?

Transcription is the process of synthesizing RNA from a DNA template.

Where in the cell does transcription take place in eukaryotes?

Transcription occurs in the nucleus.

What is the end product of transcription?

The end product of transcription is messenger RNA (mRNA).

How is transcription different from DNA replication?

Transcription synthesizes RNA, while replication duplicates DNA.

Why is transcription an important step in protein synthesis?

Transcription produces mRNA, which carries the genetic information to the ribosome for translation.

What enzyme is responsible for transcription?

RNA polymerase is the enzyme responsible for transcription.

What is the function of RNA polymerase?

RNA polymerase synthesizes RNA by adding RNA nucleotides complementary to the DNA template.

What type of RNA is produced during transcription?

Messenger RNA (mRNA) is produced during transcription.

What is the base pairing rule for RNA?

In RNA, adenine pairs with uracil, and cytosine pairs with guanine.

If a DNA template has the sequence TACGGT, what is the mRNA sequence?

The mRNA sequence is AUGCCA.

What base in RNA replaces thymine?

Uracil replaces thymine in RNA.

How does the structure of RNA differ from DNA?

RNA is single-stranded and contains ribose sugar, while DNA is double-stranded and contains deoxyribose sugar.

What is translation?

Translation is the process of synthesizing proteins from mRNA.

Where in the cell does translation take place?

Translation occurs in the cytoplasm at the ribosome.

What is the end product of translation?

The end product of translation is a polypeptide chain, which folds into a protein.

What type of RNA is read during translation?

Messenger RNA (mRNA) is read during translation.

What is the role of mRNA in translation?

mRNA carries the genetic code from DNA to the ribosome for protein synthesis.

What is the role of tRNA in translation?

tRNA brings the appropriate amino acids to the ribosome based on the mRNA codon.

What is the role of rRNA in translation?

rRNA is a component of the ribosome and helps facilitate the translation process.

What is a codon?

A codon is a sequence of three nucleotides in mRNA that codes for a specific amino acid.

What is an anticodon, and where is it found?

An anticodon is a sequence of three nucleotides in tRNA that pairs with a complementary mRNA codon.

What is the function of the ribosome during translation?

The ribosome facilitates the binding of tRNA to mRNA and catalyzes the formation of peptide bonds.

How many nucleotides make up a codon?

A codon is made up of three nucleotides.

What is the start codon?

The start codon is AUG, which signals the beginning of translation.

What amino acid does the start codon code for?

The start codon AUG codes for the amino acid methionine.

What are the stop codons?

The stop codons are UAA, UAG, and UGA, which signal the end of translation.

What happens when the ribosome reaches a stop codon?

When the ribosome reaches a stop codon, translation is terminated, and the polypeptide is released.

How many different codons are possible?

There are 64 different codons possible.

How many amino acids are coded for by mRNA?

mRNA codes for 20 different amino acids.

What is the base pairing rule between mRNA codons and tRNA anticodons?

The base pairing rule states that adenine pairs with uracil and cytosine pairs with guanine.

If the mRNA codon is AUG, what is the tRNA anticodon?

The tRNA anticodon is UAC.

If a DNA sequence is TAC-GGA-CTT, what is the corresponding mRNA codon sequence?

The corresponding mRNA codon sequence is AUG-CCU-GAA.

What is a mutation?

A mutation is a change in the DNA sequence that can affect gene function.