mitosis

Question 1

define mitosis

Answer 1

-production of two genetically identical cells, each containing a complete copy of the parental chromosomes from a parent cell

Question 2

define homologous chromosome

Answer 2

-chromosomes of the same length and shape, with the same genes from gene loci

Question 3

what is interphase

Answer 3

-the active period where protein synthesis, dna replication and increase in number of mitochondria and chloroplast in plant cell occur.

Question 4

difference in chromosomes and chromatids

Answer 4

-two dna molecules formed during dna replication are known as sister chromatids, until they are separated at the centromere during anaphase where they are then known as individual daughter chromosomes.

Question 5

describe prophase

Answer 5

-chromatin thread condenses, coils and shortens to become chromosome
-chromosome now contains two sister chromatids attached at the centromere
-in animal cells, asters made of microtubules formed around the centromere, which then move to opposite poles of the cell, formed spindle fibres between them, nucleolus disappears
-nuclear envelope disappears
-spindle forms with spindle fibres extending from one pole of the cell to the other

Question 6

describe metaphase

Answer 6

-chromosome lines up at the equator of the spindle
-the centromere of each chromosome is attached by a spindle fibre

Question 7

describe anaphase

Answer 7

-each centromere splits
-spindle fibre pulls the chromatids apart to opposite sides of the cell
-once sister chromatids are separated, they are known as daughters chromosomes

Question 8

describe telophase

Answer 8

-spindle fibre breaks down
-nuclear envelope forms around chromosomes at opposite poles of the cells
-nucleolus forms and the chromosomes uncoils and lengthens becoming chromatid threads

Question 9

describe cytokinesis (not mitosis)

Answer 9

-in animal cell, furrow appear in cytoplasm between the two nuclei
-furrow deepens and two identical daughter cells are now produced

Question 10

explain the importance of mitosis with regards to growth, repair and asexual reproduction

Answer 10

-multicellular organisms depend on mitosis for development from a fertilised cell, growth and repair of dead skin cells, muscle tears and broken blood vessels
-unicellular organism depend on mitosis for asexual reproduction where daughter cell is genetically identical to parent cell

Question 11

difference in growth of plants and animals

Answer 11

-restricted to tips of shoots and roots, occurs throughout plant lifetime
-occurs throughout animals body, stop growth after certain age or maturity

Question 12

regenerative properties of planarian worms

Answer 12

they can regenerate body parts that are cut off by growing back the parts, where the cells in the planarian divide by mitosis

Question 13

define asexual reproduction

Answer 13

-the process resulting in the production of genetically identical offspring from one parent

Question 14

what are cancerous tumour and how do they arrive

Answer 14

-undifferentiated cells that continue to divide uncontrollably
-uncontrolled mitotic cell division that can occur in any body part