3.3 and 10.1 Meiosis

Question 1

Allele

Answer 1

one of the possible alternative of a gene, occupying a specific position on a chromosome, that controls the same trait.

Question 2

Amniocentesis

Answer 2

a procedure used to diagnose genetic defects in the early stages of pregnancy; it involves collecting amniotic fluid using a needle and syringe.

Question 3

Chorionic villus sampling

Answer 3

technique for diagnosing genetic defects while a foetus is in the uterus. A small sample of the placenta is removed and analysed.

Question 4

Crossing over

Answer 4

exchange of genetic material between non-sister chromatids during meiosis I.

Question 5

Diploid

Answer 5

a cell containing two sets of chromosomes (2n), one from each parent.

Question 6

Down syndrome

Answer 6

a human genetic disease resulting from having an extra chromosome 21 (characterized by having a delay in mental development).

Question 7

Gametes

Answer 7

one of two haploid reproductive cells, egg or sperm, whose union is necessary in sexual reproduction to produce a diploid zygote.

Question 8

Germ-line cells

Answer 8

the cellular lineage of a sexually reproducing organism from which eggs and sperm are derived.

Question 9

Haploid cells

Answer 9

have one chromosome of each pair (have one full set of the chromosomes that are found in its species).

Question 10

Homologous chromosomes

Answer 10

chromosome pairs with genes for the same characteristics at corresponding loci.

Question 11

Karyotype

Answer 11

a method of organizing the chromosomes of a cell in relation to number, size, and type.

Question 12

Meiosis

Answer 12

the process of cell division in sexually reproducing organisms that reduces the number of chromosomes in reproductive cells from diploid to haploid.

Question 13

Non-disjunction

Answer 13

an error during mitosis or meiosis in which both members of a pair of homologous chromosomes or both sister chromatids fail to move apart.

Question 14

Random orientation

Answer 14

the orientation of homologous chromosomes in the spindle axis during metaphase I is random and either maternal or paternal homologue may orient towards a given pole.

Question 15

Sister chromatids

Answer 15

replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis.

Question 16

allele exchange

Answer 16

During crossing over, the switch of alleles for the same genes.

Question 17

bivalents

Answer 17

A structure in which 2 pairs of homologous sister chromatids have synapsed with one another

Question 18

chiasmata

Answer 18

The X-shaped, microscopically visible region representing homologous chromatids that have exchanged genetic material through crossing over during meiosis.

Question 19

crossing over

Answer 19

Process in which homologous chromosomes exchange portions of their chromatids during meiosis.

Question 20

diploid

Answer 20

An organism or cell having two sets of chromosomes or twice the haploid number

Question 21

fertilization

Answer 21

Male sex cell (sperm) unites with female sex cell into one cell (46 chromosomes – 23 from each).

Question 22

fusion of gametes

Answer 22

occurs when two haploids (an egg and sperm) join to form one zygote (first cell of life)

Question 23

gametes

Answer 23

A haploid cell such as an egg or sperm. Gametes unite during sexual reproduction to produce a diploid zygote.

Question 24

haploid

Answer 24

An organism or cell having only one complete set of chromosomes

Question 25

independent assortment

Answer 25

the random distribution of the pairs of genes on different chromosomes to the gametes

Question 26

non-disjunction

Answer 26

meiosis in which there is a failure of paired homologous chromosomes to separate

Question 27

non-sister chromatids

Answer 27

Chromatids from opposite members of a homologous pair. These cross over at prophase I.

Question 28

random orientation

Answer 28

the random position of each pair of chromosomes in the nucleus when the spindle microtubules become attached. Their random orientation will eventually result in which chromosomes end up where.

Question 29

synaptomenal complex

Answer 29

where cross over occurs between two non-sister chromatid to allow for cross-over

Question 30

outline some of the outcomes of sequencing the human genome

Answer 30

knowledge of location/position of human genes on chromosomes
understanding of evolutionary relationships between humans and other animals
detection of genetic diseases
enhanced research techniques
knowledge of the base sequence of genes