Unit 3 - Cell Cycle Flashcards

What is the cell cycle?

A series of events that takes place in a cell as it grows and divides

What is the “Cell Theory”

Cells arise through division of pre-existing cells

What are embryos?

Newly developing organisms

What do plants and animals start life as?

As single-celled cells (zygote)

What is mitosis?

The process when one cell divides to crate two identical twin cells so each new cell receives the same complete set of chromosomes.

Why is mitosis important/do?

Growth, repair, and the reproduction in living organism

What does mitosis produce?

Somatic (non-sex) cells

Example: Neurons, skin cells, blood cells, muscle cells, etc.

What is meosis?

A two-part cell division that creates four genetically unique cells (gametes) by reducing the number of chromosomes to half.

Why is meosis important/do?

Sexual reproduction and genetic diversity for off-spring

What does meosis produce?

Gametes (sex) cells

Example: Sperm egg cells, egg cells in the ovaries

What is a chromosome?

A single, long double helix of DNA wrapped around histones

What are histones?

The building block of chromosomes/A group of proteins that help organize and package DNA into structures called nucleosomes

What does DNA encode for?

Genetic information and proteins

What does DNA stand for?

Deoxyribonucleic acid

What is a chromatid?

One of the two identical halves of duplicated chromosomes that is joined together to the other half by a centromere

What are chromatids attached to the centromere called?

Sister chromatids

How many chromosomes do humans have and how many pairs are they organized into?

46 chromosomes that are organized into 23 pairs

What do homologous mean?

Same

What are all the cell cycle phases?

G1 (Gap 1), S Phase (Synthesis), G2 (Gap 2), and M Phase (Mitosis/Cytokinesis)

What is the purpose of the cell cycle?

Growth, repair, and reproduction in living go organisms.

More detailed: It ensures that a cell can accurately copy its DNA and device to create identical twin cells, which replaces old cells, repairing tissues, and creates new ones.

What would happen without the cell cycle?

Without the cell cycle, organisms wouldn’t grow, damage would go un-repaired, and organ systems would fail leading to death

Short answer: death

What is G1 (Gap 1)’s placement in the cell cycle and purpose?

G1 is the first stage of the cell cycle

The cell grows, copies its organelles, synthesizes proteins and RNA in preparation for DNA replication

What is S (Synthesis) phase’s placement during the Cell cycle and purpose?

The S (Synthesis) phase is the 2nd phase of the Cell Cycle

The cell synthesizes/replicates a complete copy of the DNA in its nucleus and duplicates a microtubule-organizing structure called centrosome, which helps separate DNA during mitosis

What is G2 (Gap 2)’s placement in the Cell Cycle and purpose)

G2 (Gap 2) is the 3rd phase of the Cell Cycle

The cell grows even more and makes proteins and organelles & begins to reorganize its contents in more preparation for mitosis

What is G1, S phase, and G2 known as?

The interphase

What is the M (Mitosis) phase’s placement in the Cell Cycle and purpose?

The M (Mitosis) phase is the final phase of the Cell Cycle with two processes: mitosis and cytokinesis

The one cell divides its copied DNA and cytoplasm to make two new, identical twin cells

What are the two distinct division-related processes in the M phase?

Mitosis and cytokinesis

What is cytokinesis and its purpose?

The divison of the cytoplasm is split in two, making two independent twin cells. Cytokineses takes place differently in animal and plant cells

What are kinetochores?

Large protein structures located at the centromere of each sister chromatid

What are the spindle fibers?

A bundle of microtubules that form spindle apparatus during cell division used to separate chromosomes into two twin/daughter cells

What are three types of spindle fibers?

Kinetochore fibers, polar fibers, and astral fibers.

What are the five stages of mitosis?

Prophase, pro metaphase, metaphase, anaphase, and telophase

What is prophase?

Prophase is the 1st stage of Mitosis

• Chromosomes condense

• Spindle apparatus forms

• Chronicles node toward opposite poles

What is prometaphase?

Pro metaphase is the 2nd phase of Mitosis

• Nuclear envelope breaks down

• Microtubules attach to chromosomes at kineochores

• Chromosomes are pushed and pulled by micro tubules until they reach the middle of the spindle

What is metaphase?

Metaphase is the 3rd stage of the Mitosis

• Formation of the mitotic spindle is completed

• Chromosomes are lined up on the metaphase plate - an imaginary plane between 2 spindle poles

• Each chromosome is held by kinetochore microtubules from opposite poles

What is anaphase?

Anaphase is the 4th stage of mitosis

• Sister chromatids are pulled by the spindle fibers toward opposite poles of the cell

• Kinetochore microtubules shrink

• Separates two identical sets of twin chromosomes

What is telophase?

Telophase is the 5th stage of mitosis

• A nuclear envelope/membrane is formed around each set of chromsomes

• The chromosomes begin to de-condense (uncoil)

• Mitosis is complete

• Cytokinesis occurs around the end of telophase/the cytoplasm divides to form two daughter/twin cells.

What are chromatids attached to the centromere called?

Sister chromatids

Before mitosis. each cell is ….

Replicated

What happens during prophase?

Chromsomes condense and become visible in the light microscope 

When is the spindle apparatus formed and its purpose?

During prophase and produces a mechanical force that moves replicated chromosomes during early mitosis

Where are sister chromatids pulled by the spindle fibers toward in Anaphase?

The opposite poles of the cell

Chromosomes are pushed and pulled by microtubules until they reach what in what stage?

The metaphase plate, in metaphase

When does the nuclear envelope break down?

Pro meta-phase

What do the vesicles from the Golgi appartus in Cytokinesis form? (Plants)

A cell plate

What does Cytokinesis in animals form and how?

Using a ring of actin and myosin filaments that pinches forward, it forms a clevage furrow

Which phase of the cell cycle involves the division of replicated chromosomes?

Mitosis

What structure forms at the centromere that attaches to microtubules?

The kinetochore

Where are chromosomes lined up during the metaphase?

The metaphase plate

What forms around each set of chromosomes during telophase?

A nuclear enevelope

Why are nuclear envelopes important?

They separate the nucleus from the cytoplasm and protect the cell's genetic in information

What does G1 Checkpoint do?

Checks for

• Cell size

• Nutrients

• DNA Damage

• Growth Factors

What does G2 Checkpoint do?

Checks for

• DNA Damage

• DNA Replication/completeness 

What does M (Spindle) Checkpoint do?

Checks for

• Chromosomes attachment to spindle at the metaphase plate