GENETICS VOCABULARY

SBI 3

IMPORTANT TERMS:• Genetics:

– The study of the relationship between genes and heredity• Mitosis

– Division of nucleus into two genetically identical nuclei• Meiosis

– Cell division process that involves two divisions with only one duplication of chromosomes

• Parent cell– Cell that divides by mitosis into two genetically identical

cells• Daughter cells

– Genetically identical cells produced from parent cell

IMPORTANT TERMS:• Chromatin

– Thread-like structure of DNA and proteins in nucleus• Chromatid

– Each of the two identical chromosome strands in a replicated chromosome attached by their shared centromere

• Chromosome– Carries genes, formed when chromatin condenses

Chromatid (when together

and chromosome when separated)

IMPORTANT TERMS: Gene

Segment of DNA that carries the code for a specific protein Allele

One form of a gene for specific trait (ex. If gene was eye colour, allele would be blue/brown/green)

Diploid (2n) number of chromosomes in a body cell of an organism, having two chromosomes

of each type per cell Haploid

(n) number of chromosomes in a cell that contains a single set of chromosomes, present in gametes

Somatic cells General body cells, have the diploid number of chromosomes

Sex cells Haploid reproductive cells, sperm and egg, whose union is necessary in sexual

reproduction to initiate the development of a new individual (also called gametes) Gametes

Egg and sperm cells that unite during sexual reproduction

CELL CYCLE AND MITOSIS

SBI 3

THE CELL CYCLE:

Interphase: • in between stages of dividing• G1—beginning cell growth• S—DNA duplicates (makes a copy)• DNA is in the form of chromatin• G2—cell undergoes it’s function

Purpose: to replace dead or dying cells to allow an organism to grow and

develop

interphase

MITOSIS:What is it?

– DNA copies (chromosomes) are separated & sorted into two sides of the cell

– the cell then splits in two and part of each parent is carried to the two new cells.

– each ‘daughter’ cell is identical to the parent cell

– results in cells such as internal organs, skin, bones, blood, etc.

PHASES OF MITOSIS:

• Interphase• Prophase• Metaphase• Anaphase • Telophase• Cytokinesis

IPMATC

Interphase occurs just before Mitosis begins:

DNA is replicated along with organelles and other cellular components and the cell prepares for division.

Mitosis Interphase

Animal cell Plant cell

STEP 1:Prophase (preparation phase)

• the DNA recoils, and the chromosomes condense• the nuclear membrane disappears• mitotic spindles begin to form

Nuclear membrane

Mitosis Prophase

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

Animal cellAnimal cell Plant cellPlant cell

STEP 2: Metaphase (organizational phase)

• spindle fibres attach to the chromosomes at the centromere

• chromosomes line up the middle of the cell

Mitosis Metaphase

Animal cell Plant cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

STEP 3: Anaphase (separation phase)

• the chromosomes split at the centromere• the ‘sister’ chromatids are pulled by the spindle

fibers to opposite poles of the cell.

Mitosis Anaphase

Animal Cell Plant cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

STEP 4:Telophase

• the chromosomes, the cytoplasm and organelles divide into 2 portions.

• this diagram shows the end of telophase

Mitosis Telophase

Animal cell Plant cell

Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

After Mitosis: Cytokinesis the actual splitting of

the cytoplasm into two separate cells is called cytokinesis

occurs differently in both plant and animal cells

Animal cells: cleavage furrow pinches cell

Plant cells: cell plate forms in between

Beginning of cytokinesis in a plant:

Beginning of cytokinesis in an animal:

http://www.bioweb.uncc.edu/1110Lab/notes/notes1/lab6.htm