dna

Question 0

3 types of RNA (3)

Answer 0

1. mRNA (messenger RNA) - single strand that carries the genetic code from nucleus into cytoplasm
2. tRNA (transfer RNA)- transports amino acids to ribosomes to assemble proteins
3. rRNA (ribosomal RNA)- physical and chemical structure on which protein is actually assembled

Question 1

transcription (4)

Answer 1

1. code transferring from DNA -> RNA
2. occurs in nucleus
3. RNA polymerase binds to the DNA at “promoter” and unwinds and separates the helix into 2 strands, one called the sense strand
4. as RNA polymerase unwinds the DNA it also adds RNA nucleotides, which are H bonded to DNA
5. when RNA polymerase reaches the terminating sequence on the DNA chain it breaks off the DNA

Question 2

DNA replication (3)

Answer 2

1. both stands in each chromosome are replicated
2. DNA polymerase is used, attachs and moves along DNA strand, while DNA ligase causes bonding of successive DNA nucleotides to one another using high E phosphate bonds
3. each new DNA strand is attached to a template DNA strand by a hydrogen bond

Question 3

DNA repair (proof reading and mutations) (2)

Answer 3

1. proofreading: DNA polymerase and ligases proofread the strands and cut defective areas out
2. mutations: when a mistake occurs in transcription => abnormal protein; can lead to abnormal cell function and apotosis

Question 4

chromosome replication (4)

Answer 4

1. human cell has 46 chromosomes (23 pairs)
2. DNA is packed into chromosomes and the genes are almost identical
3. DNA wrap around (+) charged histones which regulate DNA activity (when tightly wrapped around DNA cant replicate or make RNA)
4. chromosomes replicate after DNA replicate

Question 5

cell mitosis nemonic (5)

Answer 5

1. I (interphase)
2. Prefer (prophase)
3. Milk (metaphase)
4. And (anaphase)
5. Tea (telophase)

Question 6

interphase (late) (4)

Answer 6

1. lengthening of microtubles causing 2 pairs of centrioles to move apart
2. at same time other microtubles grow radially away from centriole pairs, forming a spiny star (aster) in the end of each cell
3. microtubles between the 2 centrioles = miotic spindle
4. microtubles + 2 pairs of centriole = miotic apparatus

Question 7

prophase (and late prophase/ prometaphase) (4)

Answer 7

1. chromatin condenses -> chromatids
2. nucleoli disappear
3. prometaphase or late prophase: miotic spindle is growing an punctures nuclear membrane
4. microtubles pull one chromatid of each pair towards one pole

Question 8

metaphase (2)

Answer 8

1. chromosomes cluster at middle of cell

2. centromeres align at equator of spindle

Question 9

anaphase (1)

Answer 9

1. centromeres split and are pulled to opposite sides of cell

Question 10

telophase (2)

Answer 10

1. two daughter chromosomes are now pulled apart and miotic apparatus dissolves
2. nuclear membrane forms around each set of chromosomes and microfilaments pinch to make two new cells

Question 11

cytokinesis (4)

Answer 11

1. division of cytoplasm
2. begins during late anaphase or early telophase
3. plasma membrane over center of cell is drawn inward by contractile filaments and pinched into two daughter cells
4. these daughter cells are smaller but identical and will enter interphase and grow