Topic 6 Cell Division Flashcards
What is mitosis
Cell division which produces two diploid daughter cells that are genetically identical to each other and the original parent cell which provides genetic stability
Define meiosis
Cell division which produces four haploid daughter cells that are genetically different to each other and the parent cell. The daughter cells are used to form gametes used for sexual reproduction
What are Genes
Specific regions of DNA in the chromosomes which codes for one polypeptide
What is a chromosome made up of
2 identical chromatids joined by a centromere
What is a chromosome
Long sections of DNA,proteins and a small amount of RNA
What is a cell with a full number of chromosomes known as
Diploid
What is a cell with half the number of chromosomes known as
Haploid
What does diploid mean
A cell with a full number of chromosomes
What is the centromere
The region on a chromosome that joins the two chromatids together
What is a chromatid
One of the two strands of genetic material that make up a chromosome
What are haploid cells used for
Gametes in sexual reproduction
What is the stage in the cell cycle where the cell is not undergoing cell division
Interphase
What happens in interphase
The DNA is doubled by semi conservative replication and chromosomes are replicated so each consists of two chromatids joined by a centromere
Chromosomes are not visible in interphase ??
True
Why Is it wrong to regard the cell as resting in interphase
Processes still occur including DNA replication, protein synthesis, ATP is synthesised and new organelles are produced. As well as this the amount of DNA is doubled, this is essential for mitosis to occur
Which stage is the longest stage of mitosis
Prophase
Which stage is the longest stage of the cell cycle
Interphase - accounts for 80%
What processes occur during interphase
DNA replication
New organelles are produced
Protein synthesis
ATP is synthesised
What is mitosis
Cell division which produces two diploid daughter cells that are genetically identical to each other and the original parent cell which provides genetic stability
Define meiosis
Cell division which produces four diploid daughter cells that are genetically different to each other and the parent cell. The daughter cells are used to form gametes used for sexual reproduction
What are Genes
Specific regions of DNA in the chromosomes which codes for one polypeptide
What is a chromosome made up of
2 identical chromatids joined by a centromere
What is a chromosome
Tightly coiled length of DNA and a protein
What is a cell with a full number of chromosomes known as
Diploid
What is a cell with half the number of chromosomes known as
Haploid
What does diploid mean
A cell with a full number of chromosomes
What is the centromere
The region on a chromosome that joins the two chromatids together
What is a chromatid
One of the two strands of genetic material that make up a chromosome
What are haploid cells used for
Gametes in sexual reproduction
What is the stage in the cell cycle where the cell is not undergoing cell division
Interphase
What happens in interphase
The DNA is doubled by semi conservative replication and chromosomes are replicated so each consists of two chromatids joined by a centromere
Chromosomes are not visible in interphase ??
True
Why Is it wrong to regard the cell as resting in interphase
Processes still occur including DNA replication, protein synthesis, ATP is synthesised and new organelles are produced. As well as this the amount of DNA is doubled, this is essential for mitosis to occur
Which stage is the longest stage of mitosis
Prophase
Which stage is the longest stage of the cell cycle
Interphase - accounts for 80%
What processes occur during interphase
DNA replication
New organelles are produced
Protein synthesis
ATP is synthesised
Why is mitosis important
Growth of organisms, repair or damaged tissues, and the replacement of dead cells. And asexual reproduction in some plants, and it provides genetic stability
What is the result of uncontrolled cell division
Tumours are formed
What is a tumour
Abnormal mass of tissue
What happens during prophase in mitosis
Chromatin condenses to form chromosomes which are referred to as pairs of chromatids joined at the centromere. The spindle develops and the nucleous disappears
What happens during metaphase in mitosis
The chromosomes line up at the equator of the cell and the spindle fibre attach to he chromosomes at the centromere
What happens during anaphase in mitosis
The spindle fibres contract and centromere splits and the chromatids are pulled to opposite poles of the cell
What happens during telephone in mitosis
Chromosomes unwind back to chromatin, the spindle breaks down and the nuclear envelope reforms around each group of chromosomes
What happens at the end of telephone
The cell divides by cytokinesis which forms two genetically identical daughter cells with half the amount of DNA
What happens in cytokinesis of an animal cell
Pinching in of the plasma membrane
What happens in the cytokinesis of a plant cell
A cell plate forms between the dividing cells forming the new cell wall of two cells
how many haploid cells are produced after meiosis
4
What happens during prophase I
Chromatin condenses to form chromosomes and the nuclear envelope breaks down . each chromosome is made up of two identical chromatids joined together by the centromere. Chromosomes are arranged in homologous pairs. Two chromosomes in homologous pairs form a bivalent. The chromatid’s homologous chromosomes touch at points called chiasmata.
The centrioles begin to produce the proteins for the micro tube that will form the spindle
What happens in metaphase I
Homologous chromosomes randomly arrange themselves alone the equator of the spindle. Spindle fibres attach to the chromosome at the centromere
What happens at anaphase I
The sprinkle fibres contract and the homologous pairs separate and are pulled to opposite ends of the cell. The centromere does not split, so the chromatids are not pulled apart therefore the chromosomes remain intact
What happens in telephase I
The chromosomes unwind back to chromatin and the nuclear envelope reforms around each group of haploid chromosomes
What happens at the end of telephase I
Cytokinesis occurs and 2 new cells are produced
What happens in prophase II
Spindle forms at right angles to the spindle in meiosis I
What happens in metaphase II
Chromosomes line up at the equator
, each chromosome is attached the spindle at the centromere
What happens in anaphase II
Spindle fibres contact and the centromere splits the ,chromosomes are pulled to opposite ends of the poles
What happens in telephase II
Chromosomes uncoil to form chromatin, nuclear envelope reforms, spindle disappears, cytokinesis occurs and each cell produces 2 new cells
What are the sources of genetic information and where do they occur
Crossing over , occurs during prophase I
Independent assortment,during metaphase I
Mixing of parental chromosomes at fertilisation
What happens at crossing over
Homologous chromosomes in a bivalent swap genes at points called chiasmata
What happens in independent assortment
Homologous chromosomes in bivalent a arrange themselves randomly at the equator this is a random distribution
What happens at the mixing of parental chromosomes at fertilisation
The chromosomes of both parent cells are mixed to form the diploid zygote
