General Biology finals

Cell Cycle

Consists of sequential phases of events wherein the parent cell divides and replicates DNA materials to produce two daughter cells

• For growth

• For cell differentiation

• For repair and healing of damaged tissues

• For replication of genetic materials

• For reproduction of species

Cells Undergo Cell Cycle Processes for…

Cell reproduction

Cells Division is also known as

Cell Replacement

Occurs when old cells in the body die and new cells form

Reproduction

A common process among life forms to make a new organism from one or two parent organisms

Sexual Reproduction

Involves two specialized cells, called Gametes, coming from the parents that will result to a unique offspring

Asexual Reproduction

The production of offspring from a single parent without the involvement of gametes

Binary Fission

The cell pinches apart, splits into two, then a new cell wall forms between two daughter cells

Chromosomes

An organized structure where DNA, a double-stranded molecule is tightly coiled

Deoxyribonucleic acid

What does DNA stands for?

Chromatin

Complex set of macromolecules that contain loose DNA, proteins and RNA

Sister Chromatids

identical copies formed by the replication of a chromosome

Chromatid

Refers to each strand of duplicated chromosomes

Kinetochore

Group of proteins located at the centromere that is attached to the long spindle fibers during cell division

Telomeres

Located at the end of the DNA "X" it contain genetic information that do not translate into traits 

Centromere

A region of condensed pinched chromosomes

Interphase

The longest growth period consist of 3 phases: G1, S, G2

Gap 1

Cells increase their size as their organelles double in number

Synthesis

the DNA replicates, doubling of genetic material

Gap 2

• Contains a critical checkpoint before transitioning to the next stage

• The production of enzymes occurs

Mitosis

Division of nucleus into two genetically identical nuclei containing the same full set of DNA.

Prophase

• Chromatin condenses into tightly coiled chromosomes

• Nucleolus disappears

• Spindle fibers are formed by the organized microtubules

Metaphase

Spindle fibers attached to the kinetochore of the sister chromatids facilitates the movement of the chromosomes towards the middle of the cell

Metaphase Plate

Chromosomes lined up along the plane equidistant from a microtubule region called ____________________

Anaphase

• The spindle fibers (centriole) begins to pull the sister chromatids away from each other toward the opposite ends of the cell

• Cohesin breaks down

Telophase

The 2 complete sets of identical chromosomes are now positioned at each pole of the cell, nuclear membrane starts to form back again making 2 nucleus and ready for cytokinesis

Cytokinesis

• Involves splitting the cytoplasm into two cells and completes the entire stage of cell cycle

• Starts with the formation of cleavage furrow or trench that is pulled inward by tiny strands of protein called microfilaments, the membrane begins to pinch roughly in half and close off, forming a separate cell around each nucleus 

Regulation of cell cycle

• Cells do not divide in situations where nutrients are short in supply

• Cell division is energy demanding process

• Cells do not divide when there are no instruction to divide

• These cells are usually activated by both internal (inside the cell) external (outside the cell) factors

External Factors

Come from outside the cell

Physical signals

cell-to-cell contact

Chemical signals

__________ released by the cell such as growth factors provide instruction for the other cells to grow

Erythropoietin

__________ stimulates the production of cells that become red blood cells

Contact inhibition

When a cell touches another cell, it stops dividing

Anchorage dependent

Cells only grow if surface is available and stop dividing when detached from the culture dish

Internal Factors

Come from inside the cell include several types of molecules in its cytoplasm

Kinase

An enzyme that transfers a phosphate group from one molecule to the target molecule

Cyclins

Are rapidly destroyed at certain points in the cell cycle to allow cells to progress from G1 to M stage

Kinases that help control cell cycle can be activated by a group of protein called ______

Apoptosis

Cell death or suicide

Interphase

Prophase

Metaphase

Anaphase

Telophase

Cytokinesis

46 chromosomes

How many chromosomes does a human being body cells have?

DNA

It is a double stranded molecule, is tightly coiled in an organized structure called chromosome.

Chromatin

These are responsible for packaging the DNA efficiently into smaller volume so that it fits the nucleus of a cell.

Growth factor

Protein that stimulate cell division, which have the ability to activate specific genes to trigger cell growth.

1. Interphase

2. Mitosis

3. Cytokinesis

Definite stages of cell cycle

Cleavage Furrow

Parts of a Chromosome