BIO unit 4: Cell Reproduction, Mitosis, and Meiosis

These flashcards cover key concepts related to cell reproduction, mitosis, and meiosis, including the importance of cell division, the stages of the cell cycle, mechanisms of genetic inheritance, and the processes of meiosis.

Why is cell division important?

Cell division is essential for growth, tissue repair, and replacement of old cells.

What are the three main reasons for cell division?

1) Growth and development 2) Tissue repair 3) Replacement of old cells.

What is dedifferentiation in cell biology?

It refers to stem cells which can change from unspecialized to specialized forms.

Define differentiation in cell biology.

It is the process where unspecialized cells become specialized.

What is the role of cell division in repairing damaged tissues?

Cell division is essential for replacing damaged cells to allow organisms to repair themselves.

Give an example of cells that are replaced frequently in the human body.

Red blood cells and skin cells.

What is binary fission?

A type of asexual reproduction where a single-parent cell divides into two identical daughter cells.

What are the four main stages of cell division?

1) DNA replication 2) Cell growth 3) Segregation 4) Division.

What is the function of the FtsZ protein during cell division?

It forms a ring-like structure at the cell's midpoint, aiding in division.

What is the importance of the cell cycle?

The cell cycle ensures each new cell has the correct amount of DNA and is essential for growth, repair, and reproduction.

Length of the cell cycle varies by species; how long can it take for bean plant cells?

About 19 hours.

What is interphase?

The longest part of the cell cycle where a cell prepares for division.

What happens during the G1 phase of interphase?

The cell grows and carries out normal functions while accumulating necessary resources for DNA replication.

What occurs during the S phase of the cell cycle?

DNA replication occurs, duplicating the cell’s genetic material.

What occurs during the G2 phase of interphase?

The cell continues to grow and prepares for division, checking replicated DNA for errors.

What is the mitotic phase?

The stage of the cell cycle where actual cell division takes place.

List the stages of mitosis in order.

Prophase, Metaphase, Anaphase, Telophase.

What is the purpose of the mitotic spindle?

It helps segregate chromosomes during the process of cell division.

What happens during prophase?

Chromatin condenses into visible chromosomes and the nuclear envelope begins to break down.

What occurs during metaphase?

Condensed chromosomes line up at the cell’s equatorial plane.

What is anaphase characterized by?

Sister chromatids are separated and moved toward opposite poles of the cell.

What happens during telophase?

Separated chromatids arrive at the poles and the nuclear envelope reforms around them.

Define cytokinesis.

The final step of cell division where the cytoplasm divides to form two distinct daughter cells.

What results from mitosis?

Two genetically identical daughter cells with the same number of chromosomes as the original cell.

How does mitosis maintain chromosome number?

Each daughter cell retains the diploid chromosome number as the parent cell.

What is a type of asexual reproduction where a parent cell splits into smaller identical cells?

Budding.

What is fragmentation in terms of asexual reproduction?

The body is divided into many fragments that develop into whole organisms.

Explain vegetative propagation in plants.

A form of asexual reproduction using vegetative parts such as leaves, roots, and stems.

What is the G0 phase?

A resting phase where cells are in a non-dividing state and may exit the active cell cycle.

What is the primary role of white blood cells?

To provide an immune response against infections.

What factors can cause cells to enter G0 phase?

Differentiation, senescence, lack of stimuli, and tissue repair.

Describe the regulation of the cell cycle by external events.

Initiation and inhibition of cell division are triggered by external factors such as hormones.

What is the role of hormones in the cell cycle?

They regulate the cell cycle by either promoting or inhibiting cell division.

What can happen if a cell cannot pass through a checkpoint?

It may enter the G0 phase or undergo cell cycle arrest.

What three main checkpoints exist in the cell cycle?

G1/S checkpoint, G2/S checkpoint, and M checkpoint.

What is the significance of checkpoints in the cell cycle?

They ensure genomic stability and prevent the proliferation of cells with DNA damage.

What is the function of cyclins?

They regulate the cell cycle by binding to cyclin-dependent kinases (CDKs).

What happens at the G1 checkpoint?

The cell checks for size, nutrients, growth factors, and DNA damage before entering S phase.

What checks occur at the G2 checkpoint?

It checks for DNA damage and accuracy in DNA replication before proceeding to mitosis.

What occurs at the M checkpoint?

It ensures all chromosomes are properly attached to the spindle before anaphase.

What is the law of segregation?

The principle stating that allele pairs segregate during gamete formation.

Who is credited as the father of genetic science?

Gregor Mendel.

What are Mendel's laws based on?

His experiments with pea plants on the inheritance of traits.

What is a trait in genetic terms?

A variant form of a character that is inherited and determined by genes.

What characteristics did Mendel study in pea plants?

Seed shape, seed color, flower color, and plant height.

Define heterozygous.

An organism that has two different alleles for a specific trait.

Define homozygous.

An organism that has two identical alleles for a specific trait.

What does it mean if a trait is dominant?

The trait is expressed over a recessive trait in a heterozygous condition.

What does phenotype refer to?

The observable physical or biochemical characteristics of an organism.

What does genotype refer to?

The genetic makeup of an organism that determines its traits.

What did Mendel's F1 generation reveal?

All plants were tall, indicating that the tall trait is dominant.

What is the result of the F2 generation according to Mendel’s experiments?

Three-fourths of the plants were tall and one-fourth were dwarf.

What is Mendel's contribution to the understanding of genetics?

His work laid the foundation for the laws of heredity and inheritance patterns.

What is a gamete?

A reproductive cell that contains half the chromosomes of the parent cell.

What is the purpose of meiosis?

To produce haploid gametes and maintain chromosome numbers during sexual reproduction.

What occurs during prophase I of meiosis?

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

Define crossing over.

The exchange of segments between homologous chromosomes during meiosis.

What happens during metaphase I of meiosis?

Homologous chromosome pairs align at the cell’s equator.

Describe the significance of anaphase I in meiosis.

Homologous chromosomes are pulled to opposite poles, reducing the chromosome number by half.

What is the outcome of meiosis II?

Produces four non-identical haploid daughter cells from two haploid cells.

What genetic variations occur due to meiosis?

Recombination and independent assortment lead to genetic diversity.

What is a zygote?

The fertilized egg formed from the fusion of an egg and sperm.

Describe the difference between meiosis I and meiosis II.

Meiosis I separates homologous chromosomes; meiosis II separates sister chromatids.

What is the diploid number in humans?

46 chromosomes.

How does meiosis contribute to evolution?

By introducing genetic diversity through recombination.

What are sister chromatids?

Identical copies of a chromosome joined together by a centromere, formed during DNA replication.

Define homologous chromosomes.

A pair of chromosomes (one from each parent) that are similar in length, gene position, and centromere location.

What is the difference between haploid and diploid cells?

Haploid cells (n) contain one set of chromosomes, while diploid cells (2n) contain two sets.

What are Cyclin-Dependent Kinases (CDKs)?

Enzymes that, when bound to cyclins, phosphorylate other proteins to regulate progression through the cell cycle.

What is the law of independent assortment?

The principle stating that alleles of different genes assort independently of one another during gamete formation.

What is an allele?

A variant form of a gene.

What are Mendel's two main laws of inheritance?

The Law of Segregation and the Law of Independent Assortment.

How does the Law of Segregation describe allele behaviour?

It states that the two alleles for each gene separate during gamete formation, so each gamete carries only one allele for each gene.

How does the Law of Independent Assortment describe allele behaviour?

It states that genes for different traits assort independently of one another during gamete formation, if they are located on different chromosomes.

What is a pedigree chart used for in genetics?

A diagram used to track the inheritance of a specific trait through several generations of a family.

In a pedigree chart, what do squares and circles represent?

Squares represent males, and circles represent females.

What does it mean if a symbol is shaded in a pedigree chart?

A shaded symbol indicates that the individual expresses the trait being studied (affected).

How are generations typically represented in a pedigree?

By Roman numerals (I, II, III, etc.), with the oldest generation at the top.

How are individuals within a generation typically represented in a pedigree?

By Arabic numerals (1, 2, 3, etc.) from left to right.

How does an organism's genotype relate to its phenotype?

The genotype is the genetic blueprint, which largely determines the observable physical expression (phenotype) of traits.

If an organism has a recessive allele but shows the dominant phenotype, what is its genotype?

It must be heterozygous, carrying one dominant and one recessive allele.

What are sex chromosomes?

Chromosomes that determine an individual's biological sex.

What is the XX/XY sex determination system?

A system where females have two X chromosomes (XX) and males have one X and one Y chromosome (XY), common in mammals and humans.

What is the ZW/ZZ sex determination system?

A system where females are heterogametic (ZW) and males are homogametic (ZZ), found in birds, some reptiles, and butterflies.

What is the XX/XO sex determination system?

A system where females have two X chromosomes (XX) and males have one X chromosome (XO), seen in insects like grasshoppers.

What is haplodiploidy?

A sex determination system where males develop from unfertilized eggs (haploid) and females develop from fertilized eggs (diploid), typical for bees, ants, and wasps.

How does the Y chromosome determine sex in the XX/XY system?

The presence of the SRY gene on the Y chromosome triggers male development.

Who was Thomas Hunt Morgan?

An American evolutionary biologist who established the chromosomal theory of inheritance.

What organism did Thomas Hunt Morgan primarily use for his genetic research?

The fruit fly, Drosophila melanogaster.

What was a key discovery Morgan made regarding sex-linked inheritance?

He discovered that the gene for white eye color in fruit flies was located on the X chromosome.

What concept did Morgan's work with fruit flies help establish?

The chromosomal theory of inheritance, specifically that genes are located on chromosomes.

What is gene linkage, as observed by Morgan?

The tendency of genes located close together on the same chromosome to be inherited together.

How did Morgan demonstrate that genes could be linked on a chromosome?

By observing that certain traits, like body color and wing size in fruit flies, were often inherited together.

What groundbreaking technique did Morgan's lab develop for understanding gene arrangement?

The creation of genetic maps, showing the relative positions of genes on chromosomes based on recombination frequencies.