Karteikarten
Cell division 1
Karten in diesem Stapel (29)
- 1What is classed as a chromosome? What is a homologous chromosome?-Chromsomes can either be a Single chromatid or Sister chromatid.
-A homologous chromsome is a chromosome which is the same but not identical I.E they have genes located in the same loci regions. - 2Draw and label a chromatid.
- 3Draw and label a sister chromatid.
- 4Draw and label a homologous chromosome.
- 5What are chromosome made of? What shape is DNA? What are sections of a chromosome called? How do chromosomes become visible?-Chromosome are made from histones (proteins) combined with DNA (Chromatin)
-Double helix
-Genes
-They become visible when chromatin condenses causing the chromosome to become visible - 6What is a chromatid? What is a sister chromatid?-A chromatid is one a single chromosome before it undergoes DNA replication
-A sister chromatid is a replicated chromatid joined by a centromere which has undergone DNA replication (Both the chromatids in a sis chromatid are genetically identical) - 7What is the ploidy level?-The ploidy level describes the number of complete sets of chromosomes an organism has.
I.E haploid = 2 sets
diploid = 1 set
tetraploid = 4 sets
triploid = 3 sets - 8What is the defenition of a homologous chromosome?-They are chromosomes which are the same, meaning that they have the same shape, size and carry the same gene loci in the same palce.
- 9What is mitosis? What stage happens before mitosis? What are the 4 stages which can occur in mitosis? What happens after mitosis?-Mitosis is a type of cell division which produces 2 genetically identical daughter cells.
-Interphase
-Prophase
Metaphase
Anaphase
Telephase
-Cytokensis - 10Describe the stage of interphase during mitosis?-Interphase is the longest stage of mitosis.
-It is known as the period of growth and synthesis.
-During interphase the following process' occur:
+Protein synthesis
+DNA replication/Synthesis
+Organelle synthesis
+ATP synthesis - 11Describe the stage of prophase during mitosis?-The centrioles move to opposite poles
-Spindle fibres are synthesised
-The chromatin condenses making the chromosome (sis chromatids) visible
-Nucleoulous disappears and the nuclear envelope disintegrates - 12Describe the stage of metaphase during mitosis?-The spindle attach to the centromere's of the chromosomes (sis chromatids)
-The chromosome (sis chromatids) line up at the equator of the cell - 13Describe the stage of anaphase during mitosis?-Spindle fibres contract spliting the sis chromatids to individual chromatids pulling the centromeres to the opposite poles
-The individual chromatids are pulled by the centromere to opposing ends of the cell - 14Describe the stage of telephase during mitosis?-The chromosome reach the poles of the cell and the spindle fibres break down
-The nucleolus and nuclear envelope reform - 15Describe the stage of cytokinesis during mitosis? (Animals)-The cytoplasm splits into 2 equal portions
-The cell then divides in two from the outside inwards
-This forms 2 genetically identical cells - 16Describe the stage of cytokinesis during mitosis? (plants)-The cytoplasm splits into 2 equal portions.
-Cell plates form across the centre of the cell, where the equator previously was.
-The cell wall then forms from the centre outwards separating the cells into 2 genetically identical cells - 17Describe difference between mitosis in Animals and Plants.
- 18What are the main functions of mitosis?-Production of new cells for:
+ Increasing the cell number
+ Growth
+ Repair OR replace damaged cells
+ Cell replacement (I.E skin,hair,blood cells)
+ Asexual reproduction (Offspring are genetically identical to the parents)
+ Rapid colonisation (I.e bacteria reproduction) - 19How is the cell cycle controlled? What may happen if cell division isnt controlled?-The cell cycle is controlled by genes which time and controll when cells can divide
-Cells may fail to divide and not produce new cells needed by the body
+Uncontrollable cell division (I.e too early or wrong time) which forms tumours which can be dangerous and potentially kill - 20How do genes control the cell cycle? And what happens if genes dont do this.-Genes controll the cell cycle by acting as a stopping point for cell divisions. If genes dont do this, cells will continue to divide which will lead to the formation of tumours.
- 21What are onco genes? What are proto-oncogenes?-oncogenes are the highly active cells which actually lead to the formation of cancers and tumours.
-proto-oncogenes are the none mutated version of oncogenes. they have yet to be mutated. - 22What is a malignant tumour? What is a benign tumour?-A malignant tumour is a tumour which speads quickly and is very dangerous
-A benign tumour is one which doesnt spead quickly and can easily be removed - 23What are the phases of mitosis and a brief summary of them?Inter-phase - DNA replication, DNA synthesis, Organelle synthesis, Protein/ATP synthesis
Pro-phase - Chromosome condense, centrioles move to the poles, nuclear envelope disintegrates and nucleolus disappears
Meta-phase - Attach to equator of cell
Ana-phase - Pulled to the poles of cell
Tele-phase - Arrives at the poles of the cell
Cytokinesis - Divides the cytoplasm - 24What is meiosis?-Meiosis is a two stage cell division which
takes place is sexually reproducing organisms. It produces 4 genetically different daughter cells with half the chromosome number of the parent cell. - 25Explain in terms of ploidy level what is happening in meiosis?-The parent cell chromosomes (homologous chromosomes) which is diploid (2n), is halved in meiosis I to make chromosomes(sis chromatids) (1n). The sister chromatids are then halved in meiosis II to make chromosomes(chromatids) (1n) which are haploid.
- 26What is an allele? Describe the process of crossing over.-A different form of a gene found in the same loci
-The homologous chromosomes line up chromatids cross over at points of chiasmata. This causes breaks in the chromatids to occur, and genetic information to be exchanged between bivalent chromosomes - 27In a root tip squash, why do we take cells from the root? Why do we have to squash the root tip firmly?-This is because mitosis happens within the roots.
-This is to make the tissue layer thin, and allow light to pass through the cell - 28What is the difference between a homologous pair and a bivalent pair? When do you use bivalent and homologous?-Bivalent pairs cross over and exchange chromosomal DNA. Where as homologous chromosomes are just 2 sister chromatids paired together.
-Bivalent chromosomes are used when the process is after crossing over has occurred,
and homologous if it occurs before crossing over. - 29—
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- A level Biology Karteikarten am Cell division 1, erstellt von BUKDABOSS . am 18/03/2019.
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