Bio Exam 4: Mitosis, Meiosis, and Heredity

mitosis

is the process of cell division that results in two genetically identical daughter cells, maintaining the original chromosome number.

meiosis

is a specialized type of cell division that reduces the chromosome number by half, resulting in four genetically diverse daughter cells, essential for sexual reproduction.

why is cell division important?

essential for growth, development, repair of tissues, and reproduction in organisms.

interphase

is the phase of the cell cycle in which the cell prepares for division, including DNA replication and growth, occurring before mitosis and meiosis.

G1 phase

is the first stage of interphase where the cell grows, in preparation for DNA synthesis. (Longest phase)

S phase

is the stage of interphase during which DNA replication occurs, resulting in the duplication of chromosomes to prepare for cell division.

G2 phase

is the second stage of interphase that follows the S phase, during which the cell continues to grow and produces proteins and organelles necessary for mitosis, ensuring that all cellular components are ready for division.

G0

is a resting or quiescent phase where cells exit the cell cycle and do not actively prepare for division, often remaining metabolically active.

genome

is the complete set of genetic material in an organism, including all of its genes and non-coding sequences. It contains the information necessary for growth, development, and functioning.

chromatin

is a complex of DNA and proteins found in the nucleus of eukaryotic cells, which condenses to form chromosomes during cell division. It plays a critical role in gene regulation and the organization of genetic material.

chromosomes

are structures made of chromatin that carry genetic information and become highly condensed during cell division, ensuring accurate distribution of DNA to daughter cells. (46 in humans!)

plasmid

A small, circular piece of DNA found in prokaryotes that is separate from chromosomal DNA. They can replicate independently and often carry genes that provide the organism with genetic advantages, such as antibiotic resistance.

How much DNA is in a human cell?

2 meters

gametes

are reproductive cells that unite during fertilization to form a new organism, containing half the usual number of chromosomes (haploid) and are essential for sexual reproduction.

spores

are reproductive units that can develop into a new organism, often produced by fungi and plants, and can be haploid or diploid depending on the organism.

haploid

describes a cell or organism that contains one complete set of chromosomes, typically half the number found in diploid cells, essential in the formation of gametes.

diploid

describes a cell or organism that contains two complete sets of chromosomes, one inherited from each parent, and is typical of somatic cells in many organisms.

histones

are proteins that help package and organize DNA into structural units called nucleosomes. They play a critical role in regulating gene expression and maintaining chromosome structure.

homologous

chromosomes that are similar in shape, size, and genetic content, with one set inherited from each parent, playing a key role in meiosis and genetic variation.

One member of a pair

spindle

fibers are structures made of microtubules that emerge from the centrosomes during cell division, playing a crucial role in separating chromosomes during mitosis and meiosis.

centrosome

is an organelle that serves as the main microtubule organizing center of the cell, playing a pivotal role in the separation of chromosomes during cell division by forming the spindle apparatus.

prophase

is the first stage of mitosis and meiosis, where chromatin condenses into visible chromosomes, and the nuclear envelope begins to disintegrate.

prometaphase

is the stage of cell division following prophase, during which the nuclear envelope breaks down completely and spindle fibers connect to the kinetochores of chromosomes, allowing for their alignment.

metaphase

is the stage of cell division where chromosomes align at the cell's equatorial plane, ensuring that each daughter cell will receive an identical set of chromosomes during separation.

anaphase

is the stage of cell division where sister chromatids are pulled apart toward opposite poles of the cell, resulting in the separation of genetic material.

telophase

is the final stage of cell division during which the chromosomes arrive at the poles, the nuclear envelope re-forms around each set of chromosomes, and the cell begins to undergo cytokinesis.

cytokinesis

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

checkpoints

are regulatory mechanisms in the cell cycle that ensure the proper progression through different phases, preventing damaged or incomplete cells from dividing.

G1 checkpoint

is a point in the cell cycle where the cell assesses its size, nutrients, and DNA integrity before entering the S phase, ensuring that conditions are favorable for DNA synthesis.

G2 checkpoint

are regulatory points in the cell cycle that occur after DNA replication, allowing the cell to verify that DNA has been completely and accurately replicated before proceeding to mitosis.

Difference in plant and animal cell mitosis

Plant cell mitosis involves the formation of a cell plate during cytokinesis, while animal cells form a cleavage furrow. Additionally, plant cells have a rigid cell wall that affects the shape and process of division.

prokaryote division

when the cell's single circular DNA molecule replicates, starting at the origin of replication and proceeding bidirectionally until the entire genome is duplicated, resulting in two identical daughter cells.

growth factors and kinases

are proteins that stimulate cell division and regulate various phases of the cell cycle, ensuring proper progression and response to external signals.

factors that could affect cell division

include nutrient availability, growth factors, environmental conditions, and genetic mutations that can inhibit or promote the cell cycle.

Most important checkpoint

in the cell cycle occurs at the G1 phase, where the cell assesses its size, DNA integrity, and availability of nutrients before entering S phase. This checkpoint ensures the cell is ready for DNA synthesis and subsequent division.

cancer

is a disease characterized by uncontrolled cell division and growth, often resulting in tumors. It can arise from genetic mutations that disrupt normal regulatory mechanisms.

Ignore checkpoints

Henrietta Lack

was an African American woman whose cancer cells were taken without her knowledge in the 1950s. Her cells, known as HeLa cells, became instrumental in medical research for studying cancer, vaccines, and numerous other scientific advancements.

metastasis

the spread of cancer cells from the original tumor to other parts of the body.

S phase checkpoint

A critical phase during interphase where the cell assesses DNA replication fidelity and prevents cell cycle progression if errors are detected.

M phase checkpoint

A regulatory point in the cell cycle where the cell ensures all chromosomes are properly aligned before proceeding to anaphase, preventing errors in chromosome segregation.

somatic cells

Cells that form the body of an organism, excluding germ cells involved in reproduction.

locus

sex cells

Cells involved in reproduction that give rise to gametes, such as sperm and ova. (haploid)

alleles

Different forms of a gene that arise by mutation and are found at the same place on a chromosome.

genotype

The genetic constitution of an individual, representing the specific alleles inherited from both parents.

phenotype

The observable physical or biochemical characteristics of an individual, determined by both genotype and environmental influences.

carcinogen

Any substance or agent that promotes cancer formation by causing mutations in DNA.

gender is determined by…

the combination of sex chromosomes inherited from parents, typically XX for females and XY for males.

how many pairs of autosomes?

22 pairs. These chromosomes are not involved in determining the sex of an individual.

interphase of meiosis

the stage of meiosis where the cell grows and DNA is replicated before entering meiosis I.

meiosis I

the first division stage of meiosis, where homologous chromosomes are separated into two daughter cells, leading to genetic variation.

meiosis II

the second division stage of meiosis, where sister chromatids are separated into four genetically diverse gametes.