Reproduction, the genome and gene expression 2.0 Flashcards
what happens to the mRNA after the translation process?
they travel through the nuclear membrane and the cytoplasm to attach to the ribosomes. the strand then passes though the ribosome.
describe the process of transcription: (5)
1- The mRNA strand travels through the cytoplasm and attaches to the ribosome. The strand passes though the ribosome.
2- For every three mRNA bases the ribosome lines up one complementary molecule of tRNA. We call every three bases a codon.
3- tRNA molecules transport specific amino acids to the ribosome which they leave behind shortly after lining up opposite the DNA. Because there are three mRNA bases for each tRNA molecule, we call this the triplet code.
4- Used tRNA molecules exit the ribosome and collect another specific amino acid.
5- A chain of several hundred amino acids in the correct order according to the original DNA is then made. This is called a polypeptide.
what do ribosomes do at the beginning of the transcription process?
what are the three bases called?
For every three mRNA bases the ribosome lines up one complementary molecule of tRNA.
-a codon
describe the functions of the tRNA molecules in transcription: (3)
1- tRNA molecules transport specific amino acids to the ribosome which they leave behind shortly after lining up opposite the DNA
2- Used tRNA molecules exit the ribosome and collect another specific amino acid.
3- A chain of several hundred amino acids in the correct order according to the original DNA is then made. This is called a polypeptide.
why does tRNA perfectly match with mRNA?
since the anticodons of tRNA are complementary to the mRNA
how are the proteins linked in the final stage of transcription?
Peptide bonds form between the adjacent amino acids to finalise the structure.
what are non-coding regions?
regions of DNA (genes) which do not code for proteins
what can non-coding DNA do?
switch certain genes on and off
how could some non-coding DNA affect the phenotype of an organism? (3)
-some regions of these non-coding DNA are not as good as binding to RNA polymerase.
-which means the enzyme is less likely to bind and so less protein is produced.
-if less protein is produce this can affect the phenotype of the organism.
what happens during fertilisation?
the haploid chromosomes of each parent fuse and a diploid zygote is produced
what is continuous variation?
which type of graph is used to represent it?
-variation that has no limit on the value that can occur within a population.
-a line graph
what is discontinuous variation?
which type of graph is used to represent it?
-variation that has distinct groups for organisms to belong to.
-a bar graph
how could mutations be passed on?
if the changes occur in our sex cells such as sperm and ova, there is the possibility that the changes in the gene will be passed onto the next generation.
what is monohybrid inheritance?
the inheritance of traits determined by a single gene.
