Exam 2 Study Guide CCP Bio 1111 CSCC - DNA, Mitosis & Meiosis

Chapters 7, 8 & 9: DNA

What is a nucleotide?

the basic building block of nucleic acids, composed of a nitrogenous base (A,C, G or T), a five-carbon sugar, and one or more phosphate groups.

What is a nitrogenous base?

a molecule that contains nitrogen and has the chemical properties of a base. In nucleic acids, the nitrogenous bases include adenine (A), cytosine (C), guanine (G), and thymine (T).

What are the 4 nitrogenous bases in DNA?

Adenine (A), Thymine (T), Cytosine (C), and Guanine (G).

Describe the structure of DNA.

a double helix composed of two strands of nucleotides, with a sugar-phosphate backbone and nitrogenous bases paired in the center (A with T, C with G).

What are Watson & Crick known for?

They are known for discovering the double helix structure of DNA.

What is RNA?

a single-stranded nucleic acid that plays a role in protein synthesis and gene regulation, consisting of ribose sugar, phosphate groups, and nitrogenous bases adenine (A), uracil (U), cytosine (C), and guanine (G).

How many kinds of RNA are there? Name them.

3: messenger RNA (mRNA), transfer RNA (tRNA), and ribosomal RNA (rRNA).

What is the function of mRNA?

carries genetic information from DNA to the ribosome, where it serves as a template for protein synthesis.

What is the function of tRNA?

transports specific amino acids to the ribosome during protein synthesis, helping to decode the mRNA sequence into a polypeptide chain.

What is the function of rRNA?

forms the core structural and functional components of the ribosome, facilitating the assembly of amino acids into proteins.

What molecule gets translated to make a protein?

mRNA

What 4 nitrogenous bases are found in RNA?

adenine, uracil, cytosine, and guanine. These bases pair with complementary bases during nucleic acid interactions.

What sugar is found in DNA?

Deoxyribose

What sugar is found in RNA?

Ribose

Which of the 2 types of nucleic acids is not a helix?

RNA, which is typically single-stranded, unlike DNA that forms a double helix.

What is DNA transcription?

the process by which the genetic information in DNA is copied into messenger RNA (mRNA). This process occurs in the nucleus and is essential for gene expression.

Where in the cell does transcription take place?

Nucleus

Which enzyme is involved in the process of transcription?

RNA polymerase is the enzyme that synthesizes RNA from a DNA template during transcription.

What is capping of mRNA?

the addition of a modified guanine nucleotide to the 5' end of the newly synthesized mRNA, which protects the mRNA from degradation and is important for translation initiation.

What is the addition of a poly-A tail in mRNA modification?

a series of adenine nucleotides are added to the 3' end of the mRNA transcript, enhancing stability and export from the nucleus, as well as promoting translation.

What is splicing of mRNA?

the process by which introns are removed, and exons are joined together to form a mature mRNA molecule that can be translated into a protein.

What are introns?

Non-coding sequences removed during mRNA splicing.

What are exons?

coding sequences in a gene that are retained in the mRNA after splicing, and they contain the information necessary for the synthesis of proteins.

What is the direct product of transcription?

mRNA

What is translation?

the process by which the sequence of nucleotides in mRNA is used to synthesize a specific polypeptide, resulting in protein formation. It is “read” by the ribosome to make the protein.

What is the direct product of translation?

Protein

Where in the cell does translation take place?

in the cytoplasm primarily on ribosomes.

What is a codon?

a sequence of three nucleotides in mRNA that specifies a specific amino acid or a start/stop signal during protein synthesis.

How many nucleotides makes a codon?

Three

How many possible codons are there?

64

What is an anticodon?

a sequence of three nucleotides in tRNA that is complementary to a corresponding codon in mRNA, allowing for the correct insertion of amino acids during protein synthesis.

On what molecule do you find an anticodon?

tRNA (transfer RNA)

What are some types of DNA mutations?

Substitutions, insertions, deletions , translocations, inversions

What are some causes of mutations?

environmental factors such as radiation, chemicals, or viruses, as well as errors during DNA replication.

Are all mutations bad?

No!

What are the steps of DNA replication?

initiation, elongation, and termination. During initiation, the DNA unwinds, followed by elongation where new nucleotides are added by DNA polymerase, and finally termination occurs when the replication process is complete.

What is semiconservative replication of DNA?

the process by which each new DNA molecule consists of one original strand and one newly synthesized strand. This ensures that each daughter cell inherits an exact copy of the genetic material.

What is the complementary base for thymine?

Adenine

What is the complementary base for Cytosine?

Guanine

Which process (mitosis or meiosis) creates 2 identical diploid cells?

Mitosis

Which process (mitosis or meiosis) produces 4 non-identical haploid cells?

Meiosis - The process of cell division that reduces the chromosome number by half, resulting in four genetically diverse haploid cells, typically gametes.

Which process (mitosis or meiosis) includes PMAT twice?

Meiosis

Which process (mitosis or meiosis) includes crossing over during prophase I?

Meiosis

Which process (mitosis or meiosis) forms tetrads?

Meiosis

What is the cell cycle?

the series of events that cells go through as they grow and divide, including phases such as interphase and mitosis.

What is a chromosome?

a long, thread-like structure made of tightly coiled DNA and proteins that carries genetic information. They are found in the nucleus of eukaryotic cells and are critical for cell division.

What are homologous chromosomes?

pairs of chromosomes, one inherited from each parent, that are similar in shape, size, and genetic content. They align during meiosis and are crucial for genetic variation.

How many chromosomes do humans have?

23 pairs - so a total of 46

How many chromosomes will a human sperm or egg have at the end of meiosis?

23

Are sperm and egg cells haploid or diploid?

Haploid - because the cell goes through PMAT twice in meiosis

What is the difference in haploid and diploid?

Haploid cells contain one complete set of chromosomes (n), while diploid cells have two complete sets (2n), one from each parent. Human haploid cells have 23 chromosomes while diploid ones have 46.

What is the difference in a prokaryotic and eukaryotic cell cycle?

Prokaryotic cells typically undergo a simpler process of cell division called binary fission, while eukaryotic cells experience a more complex cycle involving mitosis for growth and repair.

What happens in interphase?

the cell prepares for division. It consists of three stages: G1 (cell growth), S (DNA replication), and G2 (preparation for mitosis).

What happens in prophase of mitosis?

chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the spindle apparatus begins to form, preparing the cell for the separation of chromosomes.

What happens in metaphase of mitosis?

Chromosomes align at the cell's equatorial plane, known as the metaphase plate, and spindle fibers attach to their centromeres, ensuring proper separation during anaphase.

What happens in anaphase of mitosis?

The sister chromatids are pulled apart to opposite poles of the cell by the spindle fibers, ensuring that each new daughter cell will receive an identical set of chromosomes.

What happens in telophase of mitosis?

the chromosomes reach the opposite poles, begin to de-condense back into chromatin, the nuclear envelope re-forms around each set of chromosomes, and the cell prepares for cytokinesis to divide into two daughter cells.

What happens in G1 of interphase?

the cell grows in size, synthesizes proteins, and produces organelles necessary for DNA replication, while also carrying out its normal metabolic functions.

What happens in the S phase of interphase?

DNA is replicated (semiconservative replication), resulting in the duplication of chromosomes, so that each daughter cell will have an identical set of genetic information after cell division.

What happens in the G2 phase of interphase?

the cell continues to grow and produces proteins and organelles, while also undergoing final preparations for mitosis, including the repair of any DNA damage that occurred during replication.

What is cytokinesis?

the process that follows mitosis (after telophase) in cell division, where the cytoplasm of a parent cell is divided into two daughter cells, each containing a complete set of organelles and genetic material, and the cell membrane (and cell wall in some) forms around each.

What is the function/purpose of mitosis?

Growth and repair of damage

What is the function of meiosis?

to produce gametes (sperm and eggs) through two rounds of cell division, reducing the chromosome number by half and ensuring genetic diversity through recombination and independent assortment.

Are cells haploid or diploid after mitosis?

Diploid (complete set of paired chromosomes - 46 in humans)

Are cells haploid or diploid after meiosis?

Haploid (unpaired chromosomes - 23 in humans)

What is crossing over?

A process during meiosis where homologous chromosomes exchange segments, increasing genetic diversity.

When does crossing over occur?

Prophase I of meiosis

What are the end products of meiosis?

Gametes (reproductive cells - sperm and egg)

How does sexual reproduction increase genetic variability?

combines genetic material from two parents, resulting in offspring with a mix of traits. This process includes mechanisms like crossing over and independent assortment during meiosis.

In which process (mitosis or meiosis) do daughter cells have one chromosome from each homologous pair?

Meiosis

What process do prokaryotic cells (bacteria) use for replication?

Binary fission: This is a method of asexual reproduction where a single cell divides into two identical daughter cells.

Which process (mitosis or meiosis) produces spores in plant life cycles?

Meiosisis responsible for producing spores, which are essential for the sexual reproduction of many plants, helping in generating genetic diversity.

Which process (mitosis or meiosis) involves two division cycles (PMAT) and halves the chromosome number?

Meiosis

Which process (mitosis or meiosis) is initiated in somatic (non-sex) cells?

Mitosis

What are the 3 steps of DNA semiconservative replication?

initiation, elongation, and termination. In initiation, helicase unwinds the double helix, creating replication forks and separating the strands, which are then stabilized. During elongation, RNA primers are added to the single strands, and DNA polymerase synthesizes new complementary strands by adding nucleotides. One strand (the leading strand) is synthesized continuously, while the other (the lagging strand) is synthesized in short fragments called Okazaki fragments. Finally, in termination, RNA primers are removed, the gaps are filled with DNA, and the fragments are sealed by DNA ligase to form two identical DNA molecules.