Genetic information, variation and relationships between organisms

Question 1

Translations s

Answer 1

formation of a pp using information from the base sequence on mRNA

Question 2

Transcription

Answer 2

making an mRNA copy of a gene

Question 3

codon

Answer 3

sequence of 3 bases on mRNA that for an amino acid

Question 4

Anticodon

Answer 4

sequence of 3 bases on tRNA that are complimentary to the codon on mRNA

Question 5

tRNA

Answer 5

short single stranded RNA molecule, it has anticodon and AA binding site

Question 6

mRNA

Answer 6

single strand of RNA in a single helix

Question 7

RNA polymerase

Answer 7

enzyme that joins ribonucleotides together by forming phosphodiester bonds between the ribose sugar and phosphate group on next nucleotide

Question 8

splicing

Answer 8

removing introns that don’t code for an AA

Question 9

genetic code

Answer 9

the sequence of nucleotide bases in DNA

Question 10

degenerative code

Answer 10

AA have more than one codon

Question 11

genome

Answer 11

the complete set of genes in a cell

Question 12

proteome

Answer 12

entire set of proteins expressed by a given type of cell or organism at a given time

Question 13

describe the structure of mRNA and how it is related to its function

Answer 13

mRNA is a COPY of one strand of DNA
single stranded it possess information in the form of codons (three bases that are complementary to a triplet in DNA). The sequence of codons determines the amino acid sequence of a specific polypeptide that will be made.

Question 14

explain the process of transcription in prokaryotes

Answer 14

transcription occurs in the cytoplasm (as they have no nucleus) and the mRNA produced does not need to be spliced as there are no introns or non-coding repeats in prokaryote DNA .

Question 15

explain the process of transcription in eukaryotes

Answer 15

DNA double strand separate due to DNA helices breaking h bonds holding strand together to expose template strand. DNA polymerase to synthesis phosphodiester bond adjacent nucleotide through condensation reaction on one strand through complement base pairing forming mRNA strand where one codon is complimentary to three triplet bases, strand exits through nuclei pores Splicing is carried out by specialised proteins that form a structure known as the spliceosome. The spliceosomes recognise where an intron starts and where an intron ends. They then attach to this region and cut them out of the pre-mRNA.

Question 16

explain the process of translation

Answer 16

in the cytoplasm the mRNA attaches to ribosome. tRNAs anticodon bind to codon which is complementary. AA binded to opposite site of tRNA. another tRNA attaches ti next codon on mRNA. peptide bond formed between AA. process repeated until PPC is formed until stop codon.

Question 17

explain the specific roles of ribosomes, ATP and tRNA in translation

Answer 17

RNA molecules bind with their specific amino acids (also in the cytoplasm) and bring them to the mRNA molecule on the ribosome
The formation of a peptide bond between amino acids requires energy, in the form of ATP
The ATP needed for translation is provided by the mitochondria within the cell

Question 18

describe the structure of tRNA and how it is related to its function

Answer 18

One end of the tRNA binds to a specific amino acid (amino acid attachment site) and the other end has an anticodon that will bind to an mRNA codon.

Question 19

explain the two stages of protein synthesis

Answer 19

Transcription – DNA is transcribed and an mRNA molecule is produced
Translation – mRNA (messenger RNA) is translated and an amino acid sequence is produced

Question 20

11. Define the terms gene and allele.

Answer 20

base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA molecule
allele is a different form of a gene

Question 21

2. Explain the relationship between genes, chromosomes and DNA.

Answer 21

Chromosomes are the structures made up of chromatin. Chromatin is the threads of DNA that get condensed to form chromosomes. chromosomes are made up genes.
Genes are base sequence of DNA that codes for the amino acid sequence of a polypeptide or a functional RNA molecule

Question 22

13. Explain how genetic diversity arises during meiosis.

Answer 22

meiosis creates new combinations of genetic material in each of the four daughter cells.

Question 23

14. Distinguish between mitosis and meiosis.

Answer 23

Mitosis produces two genetically identical “daughter” cells from a single “parent” cell, whereas meiosis produces cells that are genetically unique from the parent and contain only half as much DNA.

Question 24

15. Explain the role of mutations in the formation of new alleles.

Answer 24

mutations add new alleles to a gene pool

Question 25

Explain process of meiosis

Answer 25

Only occurs in gamete forming cells. First DNA replicates during interphase. meiosis II.- The cell goes through prophase, metaphase, anaphase telophase and cytokinesis meiosis II- then goes through all these phases again. Producing 4 haploid daughter cells

Question 26

Explain meiosis 1 and 2

Answer 26

Homologous pairs of chromosomes pair up on the equator of the cell and are then pulled apart by the spindle fibres. One will have come from the father and one from the mother. Meiosis II - During the second cycle The chromosomes line up on the equator as in mitosis, they attach to spindle fibres and the chromatids are pulled apart

Question 27

Explain causes of variation during meiosis

Answer 27

independent segregation of homologous chromosomes- random distribution of chromosomes to daughter cells crossing over- during line up in equation in metaphase chromosomes can link and attach this point is the chaisma (where they break and re-join), causing new combo of alleles

Question 28

What are the types of gene mutations

Answer 28

substitution - only one AA changed deletion- frame shift insertion- frame shift

Question 29

Explain non-disjunction as a mutation

Answer 29

Non-disjunction occurs when one of the homologous pairs fail to separate fully in meiosis 1 or the chromatids don’t separate correctly in meiosis 2.

Question 30

Genetic diversity definition

Answer 30

Genetic diversity is the total number of different alleles in a population.

Question 31

Allele frequency definition

Answer 31

Allele frequency is the proportion of a population that carries a specific allele

Question 32

What factors increase genetic diversity

Answer 32

mutations-A change in the base sequence of a gene may be adventageous migrations-

Question 33

What factor decrease genetic diversity

Answer 33

founder effect-A reduction in the genetic diversity of a population caused by migration of a small colony. The resulting population has fewer varieties of alleles. Certain alleles will increase in frequency. bottle neck-A reduction in the genetic diversity of a population caused by the deaths of a large proportion of a population. The resulting population has fewer varieties of alleles. Certain alleles will increase in frequency. selective breeding-only some alleles passed on

Question 34

Explain directional bell curve of population

Answer 34

The individuals furthest from the mean are less likely to survive and pass on their alleles. The shape of the bell curve changes, getting narrower.

Question 35

What is a species

Answer 35

when two organsims can mate and produce fertile offspring

Question 36

What are the three domains

Answer 36

Archaea, Bacteria (both prokaryotes) and Eukarya (Eukaryotes)

Question 37

What are the four eukarya kingdoms

Answer 37

plants, animals, fungi and Protista