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Biology DNA questions - AQA unit 2
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- 1What are the 2 areas of non-coding DNA?-Introns (withing genes) need to be removed before protein is made
-Multiple repeat units (between genes) consist due to the same base unit being repeated many times - 2What shape is the DNA molecule?Double helix
- 3What holds complementary base pairs together?Hydrogen bonds
- 4What do triplets code for?amino acids
- 5What are transcription and translation?-they are 2 basic processes
-TRANSCRIPTION is when genetic code on a gene is used t make a mobile copy
-TRANSLATION is when code on a messenger RNA is used to make a protein - 6What a homologous chromosomes?Pairs of schromosomes with the same genes at the same loci
- 7List 3 ways in which sexual reproduction can cause variation- Crossing over of genes
-Independent Segregation
-Random Fertilization - 8In eukaryotes, DNA is ...... and wound around organizing ........ called ........In eukaryotes, DNA is LINEAR and wound around organizing PROTEINS called HISTONES
- 9What are the two types of cell division?Meiosis - one cell divides twice to produce 4 daughter cells, all of which are genetically different and has half the number of chromosomes as the parents
Mitosis - one cells divides to make 2 identical daughter cells. - 10What is the difference between haploid and diploid cells?Haploid - contain one set of chromosomes eg in human sperm cells there are 23 chromosomes
Diploid - contain 2 sets of chromosomes e.g. in a human skin cell there are 46 - 11What happens at each stage of the cell cycle?G1 phase- cell increases in volume as new cytoplasm is made, cell prepares to replicate DNA
S phase- if cell is going to divide is replicates its DNA
G2 phase - cells continues to grow, and synthesizes the enzymes and structures needed for mitosis
M phase - nucleus of cell divides by mitosis - 12What type of tumors are able to cause cancer?Malignant
- 13What are the 3 main approaches to cancer treatment?Surgery
Radiotherapy
Chemotherapy - 14Outline the main steps DNA replicationDNA replication is called semi-conservative replication.
DNA helicase enzymes attach to DNA molecule, breaking the hydrogen bonds that hold the 2 polynucleotide chains together.
DNA polymerase attaches to each strand and catalyzes the the attraction of complementary polynucleotides to the exposed bases.
Sugar phosphate bonds are formed and double helix reforms now there are 2 identical strands. - 15What are the stages of mitosis?Interphase
Prophase
Metaphase
Anaphase
Telophase - 16During mitosis what happens at Telophase ?Two sets of chromosomes group together at each pole and nuclear and a nuclear envelope forms around each group.
Chromosomes elongate, and are no longer visible under an optical microscope.
Cytokensis occurs and endoplasm splits. - 17Suggest which tissues in the body might be going through mitosis the most often.Skin, gut lining, bone marrow
- 18List four differences between mitosis and meiosisMitosis - 2 daughter cells made
-No variation (identical)
-homologous chromosomes don't pair up
-One division
Meiosis - 4 daughter cells made
-Variation created
-Homologous chromosomes pair up
-2 divisions
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- Fichas sobre Biology DNA questions - AQA unit 2 , creado por lilli.atkin el 30/04/2015.
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