The diagram below represents the six pairs of homologous chromosomes in a cell of a fruit fly before exposure to radiation (top row) and after exposure to radiation (bottom row). the appearance of the chromosomes in b indicates that exposure to radiation has caused:

image

a.

crossing over

b.
segregation & recombination

c.

chromosomal mutations

d.
non-disjunction

Describe your dna model. which part do the straws represent? the pushpins? the paper clips and the black dots you made with the marker?

You have just sequenced a new protein found in mice and observe that sulfur-containing cysteine residues occur at regular intervals. what is the significance of this finding? it will be important to include cysteine in the diet of the mice. cysteine residues are required for the formation of α helices and β pleated sheets. cysteine residues are involved in disulfide bridges that form tertiary structure. cysteine causes bends, or angles, to occur in the tertiary structure of proteins.

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic