Cell Life Cycles and Reproduction & Chromosomal Patterns of Inheritance

Flashcards reviewing key concepts from lecture notes on cell life cycles, reproduction (mitosis & meiosis), chromosomal patterns of inheritance, and related genetic concepts.

What is binary fission?

A "simple" splitting process used by prokaryotic cells for reproduction.

What is mitosis?

A "complicated" splitting process used by eukaryotic cells for reproduction.

Outline the process of binary fission in prokaryotic cells.

Cell enlarges, DNA/RNA replicates, copies move apart, plasma membrane grows inward, septum forms, and the cell divides.

What are the main stages of the eukaryotic cell cycle?

G1 stage, S stage, G2 stage, Mitotic phase (Mitosis & Cytokinesis).

What information is being processed at the G1 checkpoint?

Integrity of DNA and cyclin concentration.

What information is being processed at the G2 checkpoint?

Integrity of DNA, amount of DNA, and cyclin concentration.

What information is being processed at the M checkpoint?

Alignment of chromosomes.

What happens when a cell does not "get the go ahead" at the G1 or G2 checkpoints?

G0, DNA repair, or apoptosis.

What is apoptosis?

Programmed cell death.

When is it beneficial for a cell to undergo apoptosis?

Damaged/old cells, virus-infected cells, metamorphosing body parts, or autotomizing body parts.

When is it beneficial for a cell to proceed through mitosis/cell reproduction?

A young organism growing/developing, immune system fighting infection, or tissue needing repair/replacement.

What are stem cells?

Cells that can reproduce "indefinitely."

What are pluripotent stem cells?

Undifferentiated stem cells that can become a variety of different cell types.

What causes cancer?

Accumulation of genetic mutations leading to loss of cell cycle control.

What are the characteristics of cancer cells?

Lack of differentiation, abnormal nuclei, tumor formation, no apoptosis, metastasis (if malignant), and angiogenesis (if malignant).

What are proto-oncogenes?

Stimulatory pathway that, when mutated, can lead to rapid cell division.

What are tumor-suppressor genes?

Inhibitory pathway that, when mutated, can lead to uncontrolled cell growth due to the decrease in the production of the inhibitory proteins that halt growth or initiate apoptosis if DNA is damaged.

What is p53?

A tumor suppressor gene suspected to be present in more than half of all human cancers, inhibits cell cycle and facilitates apoptosis.

What are BRCA1 and BRCA2?

Proto-oncogenes associated with cancer development.

List the stages of cell division that should be understood relative to centrioles/microtubules, nuclear membrane, chromosomes, and cytoplasm.

Early interphase, before DNA replication; Early prophase, or just before mitosis starts; Prophase; Prometaphase; Metaphase; Anaphase; Telophase; Cytokinesis.

What are diploid cells?

Cells with two copies of genetic material where all genes occur in pairs.

What is a karyotype?

Visual display of all chromosomes from a somatic cell.

What is Mitosis?

One DNA copying event and one nuclear division that produces two daughter cells with exact same genetic material as the original cell

What is Meiosis ?

One DNA copying event and two nuclear divisions ("Meiosis I" and "Meiosis II") that produce new cells with ½ of the original genetic material

What is the ploidy result of meiosis?

Diploid (2N) à Haploid (1N)

Generally speaking, why do cells do mitosis and meiosis?

To create genetic variation for survival and reproduction.

What occurs during Prophase I of Meiosis I?

Homologous chromosomes pair during synapsis.

What occurs during Metaphase I of Meiosis I?

Homologous chromosome pairs align at the metaphase plate.

What occurs during Anaphase I of Meiosis I?

Homologous chromosomes separate, pulled to opposite poles.

What occurs during Telophase I and Interkinesis of Meiosis I?

Daughter cells have one chromosome from each homologous pair; chromosomes still consist of two chromatids.

What state are the cells in during Prophase II of Meiosis II?

Cells have one chromosome from each homologous pair.

What happens during Metaphase II of Meiosis II?

Chromosomes align at the metaphase plate.

What happens during Anaphase II of Meiosis II?

Daughter chromosomes move toward the poles.

What happens during Telophase II of Meiosis II and the result?

Spindle disappears, nuclei form, and cytokinesis takes place; results in four haploid daughter cells.

What is chromosome nondisjunction?

When chromosomes don’t split correctly.

List three causes of genetic variation in Meiosis/Sexual reproduction:

Independent assortment, genetic recombination (crossing over), and random fertilization.

What is "crossing over"?

When chromatids begin to pair up early in Meiosis I (“synapsis”), genetic material is exchanged between non-sister chromatids

Why is genetic variability a good thing?

Leads to genetic diversity among individuals in a population and better chances of surviving through environmental change, pathogen infections, etc.

What is the blending theory of inheritance?

Proposed that parental traits blend to produce intermediate offspring traits.

What is the particulate theory of inheritance?

Proposed that traits are inherited as discrete units.

What are alleles?

Alternate forms of a gene that code for one characteristic.

What is a dominant allele?

If present, will mask the expression of other allele.

What is a recessive allele?

Will only be expressed if dominant allele is not present.

What is a genotype?

Genetic information.

What is a phenotype?

Expression of the genetic information.

What does heterozygous mean?

One dominant allele, one recessive.

What does homozygous mean?

Both alleles are dom. or both rec.

What is a gene locus?

Place on the chromosome where alleles are located.

What is the mechanism by which multiple traits are passed on to offspring?

The alleles are sorted independently into the gametes.

What causes off-color shells (e.g. blue, orange, etc) in American lobsters?

A genetic mutation that causes a disruption to the pigment production pathway. This gene is recessive. The normal or “wild-type” coloration is dominant.

What are the inheritance patterns of two characteristics known in sea otters?

Fur length and fur color

What is incomplete dominance?

Where one trait is not completely dominant over the other, resulting in a blend.

What are multiple allelic traits?

Where two or more alleles can affect the phenotype

What is polygenic inheritance?

Where many genes influence a single trait

What is Pleiotropy?

Where one gene affects multiple characteristics

What is epistasis?

Where one gene can override another

What are environmental effects/phenotypic plasticity?

Where one genotype does not always lead to the same phenotype

What is Chromosome-linked inheritance:

Where a gene is located can affect the pattern of inheritance

What are some examples of Human x-linked disorders?

Color Blindness, Muscular Dystrophy, and Hemophilia