7A - 7B Genetics

Question 1

eoxyribonucleic acid (DNA)

Answer 1

a double-stranded nucleic acid chain made up of nucleotides. DNA carries the instructions for proteins which are required for cell and organism survival.

Question 2

Nucleotide

Answer 2

the monomer unit of nucleic acids. Made up of a nitrogen-containing base, a sugar molecule (ribose in RNA and deoxyribose in DNA), and a phosphate group.

Question 3

Gene

Answer 3

a section of DNA that carries the code to make a protein.

Question 4

Genome

Answer 4

the complete set of DNA contained within the haploid set of an organism’s chromosomes.

Question 5

Allele

Answer 5

alternate forms of a gene.

Question 6

Locus (pl. loci)

Answer 6

the fixed position on a chromosome where a particular gene is located.

Question 7

What is DNA

Answer 7

-forms the major component of chromosomes and contains coded genetic instructions.
-It is formed by the continuous pairing of base pairs into a longer, double-stranded nucleic acid chain.

Question 8

What is nucleotide made up of

Answer 8

A deoxyribose sugar
A phosphate group
A nitrogen-containing base

Question 9

Nitrogen-containing bases

Answer 9

-Four different kinds of nucleotides are found in DNA.

Question 10

The four bases in DNA are

Answer 10

Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)

Question 11

From DNA to genes

Answer 11

-gene is a particular section of DNA that codes for the creation of an individual polypeptide chain (protein)
-a cell will then read to make the proteins required for a range of cellular functions.
-The order of bases in the double helix determines which protein gets made

Question 12

What is a genome?

Answer 12

-Each person has two copies of each gene, one inherited from their mother and the other from their father.
-This collection of genes is called your genome,
-houses all of the genetic information needed to build and maintain you: a complex organism.
-roughly 25 000 different genes inside each of your cells.

Question 13

Alleles

Answer 13

Alleles are different forms of the same gene but with small differences in their base sequence.

Question 14

Histone protein

Answer 14

highly basic proteins that associate with DNA inside the nucleus and help it condense into a chromosome allowing it to fit inside the nucleus.

Question 15

Chromosome

Answer 15

the structure made of protein and nucleic acids that carries genetic information

Question 16

Somatic cell

Answer 16

any cell that is not a reproductive cell (such as sperm and egg cells). Somatic cells are diploid (2n), meaning they contain two sets of chromosomes – one inherited from each parent

Question 17

Chromatid

Answer 17

one half of a replicated chromosome. Prior to cell division, chromosomes are duplicated and two copies join together at their centromeres (joined chromatids are known as sister chromatids).

Question 18

Homologue

Answer 18

a homologous chromosome.

Question 19

What is a chromosome?

Answer 19

-An organism’s genome sits inside the nucleus of each of their somatic cells in the form of DNA.
-Each molecule of DNA is coiled tightly around histone proteins and packaged into thread-like structures called chromosomes.
-Human somatic cells usually contain 46 chromosomes.
-Chromosomes vary in size depending on the number of nucleotides they contain.

Question 20

Diploid (2n)

Answer 20

full set of chromosomes contained within an organism. Two copies of each chromosome. Human somatic cells have 46 chromosomes (2n = 46)

Question 21

Haploid (n):

Answer 21

having one copy of each chromosome. A set of unpaired chromosomes. Human gametes (eggs & sperm) have 23 chromosomes

Question 22

Homologous chromosomes

Answer 22

We call each of the sets of 23 chromosomes within a human nucleus a pair of homologous chromosomes

Question 23

Criteria for homologous chromosomes

Answer 23

They are the same in size and length
They have the same centromere position
They share the same genes at the same gene loci

Question 24

Karyotypes: visualising chromosomes

Answer 24

-A karyotype is a visual representation of an individual’s entire genome organised into homologous pairs.
-Chromosomes are arranged by size and centromere position into their homologous pairs.

Question 25

Autosome

Answer 25

any chromosome in humans that is not a sex chromosome

Question 26

Sex chromosome

Answer 26

a chromosome responsible for determining the biological sex of an organism.

Question 27

Aneuploidy

Answer 27

Aneuploidy refers to a chromosomal abnormality in which an organism possesses an incorrect number of total chromosomes caused by the addition or loss of an individual chromosome

Question 28

Monosomy

Answer 28

if an organism has one missing chromosome (2n - 1)

Question 29

Trisomy

Answer 29

if an organism has one extra chromosome (2n + 1)

Question 30

Tetrasomy

Answer 30

if an organism has two extra chromosomes (2n + 2)

Question 31

Polyploidy

Answer 31

-a chromosomal abnormality in which an organism has more than two sets of each chromosome
-(2n = 46), the individual would be 3n = 72 or more.
-quite common for other organisms, especially plants,