Genetics, populations, evolutions and ecosystems

Question 1

Allele

Answer 1

An alternative form of a gene that occurs at the same locus on homologous chromosomes.

Question 2

Anticodon

Answer 2

A sequence of three nitrogenous bases on a tRNA molecule that is complementary to a codon in mRNA. The anticodon enables tRNA to sequence amino acids in the order specified by mRNA.

Question 3

Apoptosis

Answer 3

Programmed cell death. Cellular DNA is degraded and the nucleus is condensed, then the cell is devoured by phagocytes.

Question 4

Carcinogen

Answer 4

Physical or chemical agent which induces cancer.

Question 5

Chiasmata

Answer 5

Observable regions in which non sister chromatids of homologous chromosomes cross over each other.

Question 6

Chromatid

Answer 6

One of the two side-by-side replicas produced by chromosome duplication.

Question 7

Chromosome

Answer 7

Structures within the cell nucleus that carry genes encoded by DNA.

Question 8

Clone

Answer 8

A group of cells or molecules that are identical by having arisen from a single ancestral cell or molecule.

Question 9

Codon

Answer 9

A sequence of three nitrogenous bases in DNA or RNA which codes for a single amino acid. Enables specific proteins to be made by specific genes.

Question 10

Crossing over

Answer 10

The exchange of genetic material between members of a pair of homologous chromosomes.

Question 11

Denaturation

Answer 11

Disruption of the structure of any complex molecule without breaking the major bonds of its chain.

Question 12

Dominance

Answer 12

Where an allele can cause a trait to be expressed in heterozygous or homozygous.

Question 13

DNA

Answer 13

Deoxyribonucleic acid. Composed of nucleic acids: deoxyribose sugar, a phosphate group and a nitrogenous base. DNA encodes for the genes that allow genetic information to be passed onto offspring.

Question 14

DNA polymerase

Answer 14

Enzymes that can synthesise new DNA strands using previously synthesised DNA or RNA as a template.

Question 15

Exon

Answer 15

The protein-coding sequences of a gene. Exons are represented in the mature RNA product.

Question 16

Gamete

Answer 16

Sex cells- sperm cells and egg cells.

Question 17

Genome

Answer 17

The entire set of genes of a gamete, person, population or species.

Question 18

Genetic code

Answer 18

The set of correspondences between base triplets in DNA and amino acids.

Question 19

Genotype

Answer 19

All of the alleles present at the locus of a blood group system.

Question 20

Haploid

Answer 20

A single set of chromosomes . Present in sperm cells, egg cells of animals, pollen cells of plants and yeast.

Question 21

Hemizygous

Answer 21

Inheritance of an X-linked gene in males.

Question 22

Heterozygous

Answer 22

The situation in which allelic genes are different.

Question 23

Homologous chromosomes

Answer 23

A matched pair of chromosomes, with one coming from each parent.

Question 24

Homozygous

Answer 24

The situation in which allelic genes are the same/ identical.

Question 25

Introns

Answer 25

The DNA base sequences that interrupt the protein-coding sequences of a gene. The non-coding sections of DNA or RNA. These sequences are transcribed into RNA but are spliced out to form the mature mRNA before translation.

Question 26

Karyotype

Answer 26

The entire chromosome complement of an individual or cell, as seen during mitotic metaphase.

Question 27

Locus

Answer 27

A specific position on a chromosome.

Question 28

Meiosis

Answer 28

The type of cell division that occurs in sex cells by which gametes having the haploid number of chromosomes are produced from diploid cells.

Question 29

Messenger RNA

Answer 29

A type of RNA molecule that conveys genetic information from DNA to the ribosome, where they specify the amino acid sequence of the protein products of gene expression.

Question 30

Mitosis

Answer 30

Cell division that results in two daughter cells with the same number of chromosomes as the parent cell. Cell division that forms all new cells except sex cells.

Question 31

Mutagen

Answer 31

Any agent that is capable of increasing mutation rate.

Question 32

Nucleic acid

Answer 32

Polymers of phosphorylated nucleosides. The building blocks (monomers) of DNA and RNA.

Question 33

Nucleoside

Answer 33

The building blocks of DNA and RNA. Compounds consisting of a purine or pyrimidine attached to ribose or deoxyribose at the 11 carbon.

Question 34

Oligonucleotides

Answer 34

Small single-stranded segments of DNA, typically 20-30 nucleotides in length, which are synthesised in vitro.

Question 35

Oncogene

Answer 35

An allele of a normal gene, called a proton-oncogene, that causes a cell to become cancerous.

Question 36

Phenotype

Answer 36

Observable characteristics of an organism.

Question 37

Plasmid

Answer 37

Cytoplasmic, autonomously replicating extrachromosomal DNA molecules.

Question 38

Recessive

Answer 38

Genes are recessive if the phenotype that they code for is only expressed when the genes are homozygous.

Question 39

Recombination

Answer 39

The formation of a new combination of alleles as a result of independent segregation or crossing-over.

Question 40

Ribosomes

Answer 40

Complexes of rRNA and protein in cytoplasm that serves as a platform for translation of mRNA into protein.

Question 41

RNA

Answer 41

Ribonucleic acid. Nucleic acids formed using DNA as a template. Similar to DNA except it has ribose in place of deoxyribose, and it has uracil instead of thymine.

Question 42

rRNA

Answer 42

Ribosomal RNA- the type of RNA found in ribosomes, the site of protein synthesis.

Question 43

Somatic cells

Answer 43

All the cells of an organism except those of the germ line. Autosomes.

Question 44

Nondisjunction

Answer 44

The failure of two members of a chromosome pair to disjoin during anaphase.

Question 45

Reverse transcriptase

Answer 45

An RNA-dependent DNA polymerase enzyme that synthesises DNA from an RNA template.

Question 46

Transcription

Answer 46

The synthesis of single stranded RNA by RNA transcriptase using DNA as a template. The process in the nucleus by which mRNA is transcribed from DNA.

Question 47

tRNA

Answer 47

Transfer RNA- the type of RNA that facilitates the translation of mRNA into a sequence of amino acids. Contains anticodons that provide the molecular link between the codons of mRNA and the amino acid sequences of proteins.

Question 48

Translation

Answer 48

The process in ribosomes by which the codon sequence of mRNA is translated into polypeptides with the help of tRNA molecules.