GENBIO Cell Reproduction

Cell Cycle

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

Cell Division

• Also known as cell reproduction

• It allows organisms to reproduce asexually, grow, and repair worn-out or damaged tissues

Cell Replacement

Occurs when old cells in the body die and new cells form; such as red blood cells, intestinal cells and skin cells

red bone marrow

Cell Division occurs in the ____________ of your bones such as in the ribs, breastbone, vertebrae and hips to continuously make new red blood cells

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

simple cell division

Bacteria and other unicellular organisms reproduction involves this kind of cell division

Binary Fission

The bacteria 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 

Histones

DNA-associated proteins that wound together chromosomes

46

How many chromosomes are in a body

Chromatin

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

-responsible for packaging the DNA efficiently into smaller volumes so it fits the nucleus of a cell

Sister Chromatids

-identical copies formed by the replication of a chromosome

-two chromatids put together

Kinetochore

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

Telomeres

Structures located at the ends of DNA molecule; contains repeated nucleotides which contain genetic information that do not translate into traits

Role: to prevent the ends of chromosomes attaching to one another and prevent the loss of genes

Interphase, Mitosis, Cytokinesis

Stages of Cell Cycle

Interphase

The growth period in the cell cycle and is divided into three parts; Gap 1, Synthesis, Gap 2

Gap 1

• Spends most of their life cycle in this phase and is the longest phase

• Cells increase their size as their organelles double in number

Synthesis

• Replication occurs

• Microtubules (protein complex) are produced in this stage

• The two strands of each DNA molecule unzips and separate during the replication 

• Each strand used as a template to form a new and complementary DNA strand

• Chromosomes doubled after synthesis

Gap 2

• Contains a critical checkpoint before transitioning to the next stage

• The production of enzymes occurs

• Makes sure that everything is in order including growing to its correct size and duplication DNA without damage

Cell theory

all living things are composed of cells, and that all cells come from preexisting cells

Chromatid

refers to each strand of the duplicated chromosome

Centromere

holds the chromatids together; a region of condensed pinched chromosomes

Mitosis

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

-The hereditary material of the parent cell is given to the daughter cells

Prophase

• Chromatin condenses into tightly coiled chromosomes

• Chromosomes are packaged into neat bundles to move them around easily when division starts

• Nucleolus disappears

• Spindle fibers are formed by the organized microtubules, grows from the centrosome and extend toward the center of the cell toward the opposite poles

• The chromosome is being prepared to line up at the center of the cell by the end of this phase

Metaphase

• ____ means after

• Alignment at the center

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

• Chromosomes lined up along the plane equidistant from a microtubule region called Metaphase Plate

Anaphase

• _____ means up or back

• Once this phase begins, the cohesin (ring-shaped protein complex) breaks down and the sister chromatids separated from each other

• Spindle fibers pulls the sister chromatids towards the opposite ends of the cells

Telophase

• ____ means end

• Two complete sets of identical chromosomes are now positioned at each pole of the cell

• The microtubules and spindle fibers disintegrate once they are no longer needed

• Nuclear membrane starts to form

• Chromosomes unfold back into chromatin

• Nucleoli reappear and the cell continue to elongate

Cytokinesis

• The actual separation

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

• Typically starts to occur in the late anaphase or telophase

• Differs in animal and plant cells

External factors

Comes from outside the cell that are in the form of messages from nearby cells or from remote parts of the organism’s body

Physical signals

Such as cell-to-cell contact, exist between 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

Chemical signals

Released by the cell such as growth factors to provide instructions for other cells to grow

Growth factors

Are proteins that stimulate cell division, which have the ability to activate specific genes to trigger cell growth

Erythropoietin

Stimulates the production of cells that become red blood cells

Internal Factors

come from inside the cell that include several types of molecules on its cytoplasm

Kinase

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

• Can be activated by cyclin

Cyclin

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

Deoxyribonucleic acid

meaning of DNA