Genetic Information, Variation And Relationship Between Organisms

Question 1

What are the characteristics of prokaryotic DNA molecules?

Answer 1

Short, circular, not associated with proteins.

Prokaryotic DNA is distinct from eukaryotic DNA in structure and association with proteins.

Question 2

How are DNA and histones organized during cell division in eukaryotes?

Answer 2

Into structures called chromosomes.

This organization is crucial for the proper segregation of genetic material.

Question 3

What is a gene?

Answer 3

A sequence of DNA bases that codes for the specific amino acid sequence of a polypeptide.

Genes are fundamental units of heredity in living organisms.

Question 4

What is the composition of a homologous pair of chromosomes?

Answer 4

One maternal and one paternal chromosome.

Homologous chromosomes carry the same genes at the same loci.

Question 5

What are alleles?

Answer 5

Different forms of a gene.

Alleles can result in variations in traits among individuals.

Question 6

What does the term ‘locus’ refer to in genetics?

Answer 6

A fixed position on a particular DNA molecule or chromosome.

Each gene occupies a specific locus on its chromosome.

Question 7

What defines diploid cells in terms of chromosomes?

Answer 7

They have chromosomes in pairs, one inherited from each parent.

Diploid organisms typically have two sets of chromosomes.

Question 8

True or False: Eukaryotic DNA molecules are short and circular.

Answer 8

False.

Eukaryotic DNA molecules are long and linear.

Question 9

What do mitochondria and chloroplasts contain?

Answer 9

DNA that is short, circular, and not associated with proteins.

This type of DNA is similar to prokaryotic DNA.

Question 10

What is the role of histones in eukaryotic cells?

Answer 10

To associate with DNA and help organize it into chromosomes.

Histones play a critical role in the packaging of DNA.

Question 11

Fill in the blank: A homologous pair of chromosomes carries the same genes in the same _______.

Answer 11

loci.

Loci are the specific locations of genes on chromosomes.

Question 12

What is the structure of DNA?

Answer 12

Twisted double helix with two polynucleotide chains

Question 13

What are the four nitrogenous bases in DNA?

Answer 13

• Adenine
• Cytosine
• Guanine
• Thymine

Question 14

How many pairs of chromosomes are found in the human nucleus?

Answer 14

23 pairs

Question 15

What is a gene?

Answer 15

A section of a chromosome that codes for a particular protein

Question 16

What is the role of histones in eukaryotes?

Answer 16

DNA is wound around proteins called histones

Question 17

What type of bond joins amino acids together?

Answer 17

Peptide bond

Question 18

How many bases code for one amino acid?

Answer 18

3 (triplet code)

Question 19

What is the significance of DNA mutations?

Answer 19

They provide genetic diversity

Question 20

What is the difference between RNA and DNA?

Answer 20

RNA contains ribose instead of deoxyribose and has uracil instead of thymine

Question 21

What is the process of DNA replication?

Answer 21

• DNA strands separate
• Hydrogen bonds broken
• DNA helicase
• Complementary base-pairing
• A with T and C with G
• Nucleotides joined by DNA polymerase
• Forming phosphodiester bonds
• Semi-conservative

Question 22

What is the function of RNA polymerase?

Answer 22

Catalyses condensation reactions between RNA nucleotides to produce a polynucleotide chain

Question 23

What is meant by the term ‘degenerate’ in the context of the genetic code?

Answer 23

More than one codon can code for the same amino acid

Question 24

What is a start codon?

Answer 24

A codon that signals the start of translation (AUG)

Question 25

What is a stop codon?

Answer 25

A codon that signals the termination of translation (UAA, UAG, UGA)

Question 26

What are introns?

Answer 26

Non-coding sequences within genes

Question 27

What is the difference between mRNA and tRNA?

Answer 27

* mRNA: Linear structure, carries codons, formed in nucleus * tRNA: Clover-leaf shape, carries amino acids, formed in cytoplasm

Question 28

Fill in the blank: The complete set of genes in a cell is called the _______.

Answer 28

Genome

Question 29

Fill in the blank: The proteins a cell can produce is called the _______.

Answer 29

Proteome

Question 30

What are the types of mutations?

Answer 30

* Substitution * Deletion * Addition (insertion) * Duplication * Inversion * Translocation

Question 31

What is an allele?

Answer 31

A version of a gene

Question 32

What is the consequence of a deletion mutation?

Answer 32

Often results in a non-functional protein

Question 33

What is the consequence of an addition mutation?

Answer 33

Can cause a frame shift in the genetic code

Question 34

What is genetic diversity?

Answer 34

Showing a great deal of variety within a population

Question 35

How does sexual reproduction contribute to genetic diversity?

Answer 35

* Independent segregation * Crossing over * Random fusion of gametes at fertilization

Question 36

True or False: Mutations always lead to negative consequences.

Answer 36

False

Question 37

What is the role of tRNA in protein synthesis?

Answer 37

Carries specific amino acids to the ribosome

Question 38

What happens during transcription?

Answer 38

* Hydrogen bonds broken * DNA uncoils * RNA nucleotides line up alongside DNA bases * RNA polymerase joins RNA nucleotides

Question 39

What is the function of ribosomes in translation?

Answer 39

Synthesize proteins using information provided by mRNA

Question 40

What is deletion in the context of mutations?

Answer 40

Removal of one or more bases ## Footnote Often results in a non-functional protein

Question 41

What does addition (or 'insertion') refer to in mutations?

Answer 41

Adding of one or more bases ## Footnote Can lead to a frame shift

Question 42

Define duplication in genetic mutations.

Answer 42

One or more bases is repeated ## Footnote Results in a frame shift

Question 43

What is inversion in the context of genetic mutations?

Answer 43

A sequence of bases is reversed ## Footnote Alters the order of bases

Question 44

Explain translocation in genetic mutations.

Answer 44

A sequence of bases is moved from one location in the DNA molecule to another part of the genome ## Footnote Can affect gene expression

Question 45

What is the effect of altering the base sequence of a gene coding for an enzyme?

Answer 45

Different sequence of amino acids ## Footnote Leads to altered position of H/ionic/disulphide bonds and different tertiary structure

Question 46

How does a mutation affect the active site of an enzyme?

Answer 46

Altered shape of active site ## Footnote Not complementary to substrate, resulting in no enzyme-substrate complexes

Question 47

What type of mutation has the greatest impact?

Answer 47

Deletion leading to frameshift ## Footnote Alters multiple amino acids

Question 48

What is the result of a substitution mutation?

Answer 48

Change in one codon ## Footnote May alter one amino acid or maintain the same amino acid due to degeneracy

Question 49

What can high energy radiation cause in terms of mutations?

Answer 49

Can cause deletion of one or more bases ## Footnote Includes ionizing particles like α, β, γ rays

Question 50

What happens to the sequence of bases in mRNA after a deletion mutation?

Answer 50

Sequence of bases in mRNA would change ## Footnote Resulting in a different sequence of amino acids

Question 51

True or False: A single substitution mutation can change the entire protein structure.

Answer 51

False ## Footnote It may alter only one amino acid or maintain the same due to degeneracy

Question 52

Fill in the blank: The mutation that causes sickle cell anemia involves a substitution of _______.

Answer 52

valine for alanine

Question 53

What is a chromosome?

Answer 53

A structure that carries genetic information.

Question 54

What is a centromere?

Answer 54

The region of a chromosome where sister chromatids are joined.

Question 55

What are sister chromatids?

Answer 55

Identical copies of a chromosome connected at the centromere.

Question 56

What is a homologous chromosome?

Answer 56

A pair of chromosomes with the same genes at the same loci.

Question 57

What happens to homologous pairs during meiosis?

Answer 57

They split up during Meiosis I.

Question 58

What is the diploid number in humans?

Answer 58

46 chromosomes (2n = 46).

Question 59

What does 'n' represent in genetics?

Answer 59

The haploid number of chromosomes.

Question 60

What is semi-conservative DNA replication?

Answer 60

The process where each new DNA molecule contains one original strand and one new strand.

Question 61

What occurs during Meiosis I?

Answer 61

Homologous pairs separate.

Question 62

What occurs during Meiosis II?

Answer 62

Sister chromatids separate.

Question 63

What is the significance of independent segregation?

Answer 63

It leads to genetic variation by creating different combinations of maternal and paternal chromosomes.

Question 64

How many possible gametes can be formed from 23 homologous pairs?

Answer 64

8,388,608 different combinations.

Question 65

What is crossing over?

Answer 65

The exchange of genetic material between homologous chromosomes during prophase I.

Question 66

How does crossing over increase genetic variation?

Answer 66

It creates different combinations of alleles.

Question 67

Why is meiosis important?

Answer 67

It produces haploid gametes and leads to genetic variation.

Question 68

What is the outcome of random fusion of gametes at fertilization?

Answer 68

It further increases genetic variation.

Question 69

Fill in the blank: A pair of unreplicated chromosomes is called _______.

Answer 69

1 chromosome.

Question 70

Fill in the blank: The first division of meiosis is called _______.

Answer 70

Meiosis I.

Question 71

Fill in the blank: The second division of meiosis is called _______.

Answer 71

Meiosis II.

Question 72

True or False: Homologous pairs are pulled apart during anaphase I.

Answer 72

True.

Question 73

What does 'haploid' mean?

Answer 73

Having one complete set of chromosomes.

Question 74

What does 'diploid' mean?

Answer 74

Having two complete sets of chromosomes.