BIO EXAM 3 WCU

What are the functions of cell division?

It is primarily for reproduction, growth/development or to repair tissue growth.

Relate the following to eachother: chromatin, chromosome, chromatid, and centromere

Chromatin is DNA and proteins.
Chromosomes are condensed DNA.
Chromatid is one half of a duplicated chromosome (two sisters make one chromosome).
Centromeres are where chromatids are closely attached.

Phases of cell cycle

Interphase and mitotic phase.
Interphase: (90%)
- G1
- S
- G2
Mitotic Phase: (10%)
- Prophase
- Anaphase
- Telophase
- Cytokinesis

Describe G1 phase of cell cycle (interphase)

Cell growth

Describe S phase of cell cycle (interphase)

Cell growth and DNA synthesis

Describe G2 phase of cell cycle (interphase)

Cell growth

Describe G0

- Non-dividing cell
- Most cells in our body are in this phase

Describe mitotic(M) phase in cell cycle

Distribution of chromosomes into two daughter nuclei (mitosis)
Division of cytoplasm, creating two new daughter cells. Each daughter can start its own new, cell cycle (cytokinesis)

What is the importance of the G1 and M checkpoints?

The G1 checkpoint is a major controller, a restriction point. This is where the cell decides whether or not to divide. Once past this phase, a cell cannot stop the cell cycle. (checks for cell size, nutrients, growth factors, and DNA damage)

The M phase is the ‘spindle checkpoint’ This is where the cell examines if the sister chromatids are correctly attached to the spindle microtubules. If a chromosome is misplaced, the cell pauses mitosis. “Divide or wait”, prevents mitosis from pulling apart sister chromatids.

What is the G0 phase?

Resting stage cells are in, not dividing.

How is control of the cell cycle relevant to cancer?

Cells use density dependent inhibition to detect if there are any problems with the environment. This helps prevent issues with DNA replication errors. The reason is, cancer does NOT respond to these signals to halt replication.

Tumors: Cancer cells that are NOT eliminated by immune system
Benign tumors remain in place
Malignant tumors invade surrounding tissue

Mitotic phase

G2 last phased of interphase, DNA is uncondensed and the nuclear membrane is intact. The two centrosomes organize the microtubules.

Phases of mitosis

Prophase, metaphase, telophase, and cytokinesis.

Describe prophase

First phase of mitosis, DNA condenses to create sister chromatids. Mitotic spindle forms and pushes centrosomes.

Describe prometaphase

Prometaphase occurs between prophase and metaphase.
The nuclear envelop disintegrates and kinetochore anchor on each sister chromatid. Some microtubules connect to kinetochores.

Non-kinetochore microtubules.

Describe metaphase

Easily seen under microscope. Chromosomes line up on meaphase plate. M checkpoint

Describe anaphase

Sister chromatids separate, proteins holding together sister chromatids are cut

Kinetochores move towards centrosomes
(Pacman mech)
Cell elongates

Describe telophase

Nuclear envelope reforms

Microtubules are gone
Cytokinesis, cleavage furrow pinches cell into two
(Plant cells form a cell plate during telophase, golgi sends vesicles to form plant cell, plate merges w cell wall eventually)

Describe cytokinesis

Process where the cytoplasm divides, resulting in two separate daughter cells. In animal cells, a cleavage furrow forms, while in plant cells, a cell plate develops.

When is DNA replicated and why is it so critical?

DNA is replicated during the S phase of interphase to ensure that each daughter cell receives an exact copy of the genetic material during cell division.

What is the difference between replicated and unreplicated chromosomes?

Replicated chromosomes consist of two sister chromatids joined at a centromere, whereas unreplicated chromosomes consist of a single chromatid. This distinction is crucial during cell division, as replicated chromosomes ensure accurate segregation of genetic material.

Does mitosis change ploidy? How do the daughter cells compare to the parent cell?

Mitosis does not change ploidy; the daughter cells are genetically identical and maintain the same number of chromosomes as the parent cell.

What is the mitotic spindle?

The mitotic spindle is a structure composed of microtubules that helps separate chromatids during mitosis. It ensures that each daughter cell receives the correct number of chromosomes by facilitating their movement to opposite poles of the cell.

What role does the mitotic spindle play in mitosis?

The mitotic spindle is responsible for organizing and segregating chromosomes during mitosis, ensuring that each daughter cell receives the correct number of chromosomes.

What is cytokinesis?

Cytokinesis is the process that follows mitosis, where the cytoplasm of a parental cell divides into two daughter cells, completing cell division.

What is the difference of cytokinesis between animal and plant cells?

Cytokinesis in animal cells involves the formation of a cleavage furrow that constricts the cell membrane, while in plant cells, a cell plate forms along the equatorial plane, eventually developing into a new cell wall.

What is the difference between mitosis and cytokinesis?

Mitosis is the process of nuclear division where the sister chromatids are separated, while cytokinesis is the subsequent division of the cytoplasm, resulting in two daughter cells.

What is binary fission?

Binary fission is a form of asexual reproduction in single-celled organisms, where the cell divides into two equal parts, each developing into a new organism. This process is common in prokaryotes, such as bacteria.

How does binary fission compare to cell division in eukaryotes?

Binary fission is a asexual reproduction method in prokaryotes where the cell divides into two identical units, while eukaryotic cell division involves multiple phases including mitosis and cytokinesis to ensure accurate distribution of genetic material.

What is a gene?

A gene is a segment of DNA that contains the instructions for building proteins, which are essential for the structure and function of living organisms.

What is a locus?

A locus is a specific, fixed position on a chromosome where a particular gene or genetic marker is located. It is important for identifying the location of genes and understanding their function.

What is sexual reproduction?

Sexual reproduction is a biological process in which two parent organisms contribute genetic material to produce genetically diverse offspring. This process typically involves the fusion of gametes, resulting in a zygote that undergoes development into a new organism.

What asexual reproduction?

A type of reproduction that involves only one parent, resulting in offspring that are genetically identical to the parent. This process includes methods like binary fission, budding, and vegetative propagation.

What is ploidy?

Ploidy refers to the number of sets of chromosomes in a cell. It categorizes organisms based on their chromosome count, such as haploid (one set), diploid (two sets), and polyploid (more than two sets).

How does ploidy alternate in life cycles?

Ploidy alternates between haploid and diploid stages in the life cycles of many organisms, particularly in plants and some fungi. This alternation allows for genetic diversity through sexual reproduction during the diploid phase, followed by meiosis to produce haploid gametes.

How does ploidy change through meiosis?

Meiosis reduces the chromosome number by half, changing diploid cells into haploid gametes, which allows for sexual reproduction and genetic diversity.

How does ploidy change through fertilization?

During fertilization, two haploid gametes fuse to form a diploid zygote, restoring the diploid state in the organism's life cycle.

Define ploidy in terms of chromosomes and alleles

Ploidy refers to the number of sets of chromosomes in a cell, determining the number of alleles for each gene. In diploid organisms, cells contain two sets of chromosomes, one from each parent, while haploid organisms have only one set.

Describe the role of mitosis and meiosis in eukaryotic sexual reproduction

Mitosis is responsible for the growth and maintenance of somatic cells, producing identical diploid cells, while meiosis generates haploid gametes for sexual reproduction, ensuring genetic diversity through recombination.

What are homologous chromosomes?

Homologous chromosomes are pairs of chromosomes in a diploid organism that have the same structure and gene sequence, one inherited from each parent. They may carry different alleles for certain genes, contributing to genetic diversity.

What are autosomes and sex chromosomes?

How many autosomes and sex chromosomes do you have?

Compare and contrast meiosis and mitosis

Describe the phases of meiosis

Describe prophase I

Describe metaphase I

Describe anaphase I

Describe telophase I and cytokinesis

Describe prophase II

Describe metaphase II

Describe anaphase II

Describe telophase II and cytokinesis

Why is it important that homologous chromosomes pair in meiosis?

When does ploidy change during meiosis?

How does sexual reproduction increase genetic variation, why is this important?

What is independent assortment, when does it happen and why does it matter?

What is crossing over and when does it happen, why does it matter?

How does crossing over results in recombination

What is the parental type?

What is a recombinant type?

How did Mendel’s work reveal particulate rather than blending inheritance?

Define diploid

Define haploid

Define homozygous

Define heterozygous

Define true-breeding

Define genotype

Define phenotype

Define phenotype

Define dominant

Define recessive

What is a monohybrid cross? How does it reveal dominance? What are the genotypic ratios?

What is a 3:1 phenotypic ratio? How does it reveal dominance? What are the genotypic ratios?

Law of segregation in terms of homologous chromosomes?

What is a testcross and what is it used for? Why?

What is the law of independent assortment in terms of non-homologous chromosomes?

Why do we need dihybrid cross to see independent assortment?

Relate parental and non-parental (recombinant) types to see independent assortment

Compare and contrast complete dominance with incomplete dominance AND codominance

How can dominance depend on the level of phenotype?

What is epistasis

How is epistasis different from simple mendelian inheritance

What is polygenic inheritance and how does it explain quantitative characters?

What are the two mendel’s laws in terms of chromosomal behavior?

Explain how some diseases are passed recessively and how others are passed dominantly

What is sex linkage and why does it matter

Relate the term hemizygous to: homozygous, heterozygous, and ploidy

What does it mean that two genes are linked and do they assort independently?

What is a wild type and is it always dominant?

What is recombination frequency? How is it related to linkage?

What are the types of chromosomal mutations and it’s effects

What is the basic structure of the double-stranded DNA molecule

Why are hydrogen bonds involved in the double helix?

What are the rules of base pairing and how it relates to DNA replication

What are the roles of polymerase and ligase in DNA replication

What is central dogma, why is it important?

What is gene expression?

Compare and contrast transcription and translation. They do what and where?

What is a codon? How is this related to genetic code

What is a reading frame? How is this related to genetic code