Cell Division Flashcards
What is cell continuity
That cells developed from pre existing cells
What are chromosomes
Coiled threads of DNA and protein visable in the nucleus during cell division
What happens to a cell when it forms from an existing cell
Produced material needed
Grows larger
Reproduced new cells
What are chromosomes called when they are long and not dividing
Chromatin
What is a gene
Section of DNA that contains instructions of a protein
What is a haploid cell
A cell that has one set of chromosomes it has one of each type of chromosome in the nucleus
What is a diploid cell
A cell that has two sets of chromosomes in the nucleus
What is
A) haploid represented by
B) diploid represented by
A) n
B) 2n
What are chromosomes that have similar genes
Homologous pair
What is the cell cycle
The changes that take place Ina cell between one cell division and the next
What is interphase
When the cell is not dividing
What do cells do during interphase
Produced organelles such as mitochondria and chloroplasts and chemicals needed for growth (start)
Produce identical copies of itself (end)
What is mitosis
A form of nuclear division in which one nucleus divides into two containing the same number of chromosomes with identical greens
What happens in stage one of mitosis
Chromosomes contract and become visible in nucleus
Each chromosome appears as a double strand
Fibres begun to appear
Nuclear membrane begins to break down
What happens in stage 2 of mitosis
Membrane is fully broken down
Chromosomes line up across the middle
Two fibres attach to each chromosome
What happens in stage 3 of mitosis
Fibres contract chromosomes are pulled apart
Each half of a chromosome is pulled to a different side of the cell
What happens in stage 4 of mitosis
Nuclear membrane surrounds each if the twinsets of chromosomes.
Chromosomes elongate and become chromatin
What are the functions of mitosis
Unicellular organism use it as a method of reproduction. Eg amoeba
Multicellular cells use it for growth and repair e.g. A zygote into an embryo.
What is cancer
Group of disorders in which cells lose their ability to control rate if mitosis and number of times it takes place.
What is benign cancer
Non life threatening
What is malignant cancer
Is an uncontrolled multiplication of abnormal cells
Could be life threatening
What are cancer causing genes
Oncogenes
What are cancer causing agents
Carcinogens Eg cigarettes
What is meiosis
Nuclear division in which the four daughter cells contain half the chromosomes number of the patent nucleus
Functions of meiosis
Allows new combination of genes
Sexual reproducing involving gametes
What happens in prophase
Chromatin contracts
Chromosomes become visible as double strand structures across the centromere
Nucleus disappears
Fibres th appear in the cytoplasm are called spindle fibres
Nucleus membrane breaks down
What happens in metaphase
Membrane completely breaks down
Spindle fibre from each end attaches to each centromere chromosomesline up across the middle
What happens in anaphase
Spindle fibre contracts
One strand from the double stranded chromosome is pulled to each end of the cell
Shortest phase
What happens in telophase
Chromosomes lengthen and become hard to distinguish
Spindle fibre breaks down
Nucleoli begins to re form
Nuclear membrane forms around the chromatin
What is a cleavage furrow
A shallow groove that divides a cell
