Topic 3.2: Chromosomes Flashcards Preview

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Flashcards in Topic 3.2: Chromosomes Deck (25)
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1

Prokaryotes chromosomes

a) Have a single circular molecule made of naked DNA (Genophore)
b) May have additional plasmids

2

Eukaryotes chromosomes

a) Multiple linear DNA molecules packaged with histones
b) Do not have plasmids

3

Plasmids

Small, autonomous circular DNA molecules

4

Centromere

Constriction point of a chromosome
a) p-arm (short)
b) q-arm (long)

5

Identifying the region in which a gene is positioned

a) Chromosome
b) Arm
c) G band location

6

Homologous Chromosomes

Paired chromosomes inherited from both parents in sexually reproducing animals

7

Characteristics of Homologous Chromosomes

a) Structural features
b) Genes at the same loci positions

8

Diploid

a) Two sets of chromosomes
b) Somatic cells in the organism

9

Haploid

a) One set of chromosomes
b) Sex cells / Gametes

10

Number of chromosomes in humans

23 pairs of chromosomes

11

Homologous Autosomes

a) 22 pairs
b) Do not determine sex

12

Sex chromosomes

a) 23rd pair
b) XX / XY

13

Y Chromosome

Contains the genes for developing male sex characteristics (SRY gene)

14

Karyotype

Identify the number and types of chromosomes in a eukaryotic cell

15

Functions of karyotyping

a) Identify the sex of offspring
b) Diagnose potential chromosome abnormalities

16

Processo of karyotyping

a) Harvesting cells
b) Chemically inducing cell division, arresting mitosis while the chromosomes are condensed
c) Determine whether chromosomes appear with sister chromatids or not

17

Karyogram

Visual profile that shows the chromosomes of a
cell in homologous pairs of decreasing length

18

Autoradiography (John Cairns)

Technique for measuring the length of DNA molecules while uncoiled

19

Process of Autoradiography

a) Radioactive thymidine is incorporated into a cell’s DNA
b) Chromosomes were fixed to a photographic surface and treated with silver bromide (AgBr)
c) Radiation converts silver ions into insoluble grains that is visible via electron microscopy when a film is developed

20

Chromosome number and species

Chromosome number is a characteristic feature of members of a particular species

21

What happens if two organisms with different diploid numbers interbreed?

a) Unlikely to interbreed
b) Offsprings are infertile (Donkey 62 + Horse 64 = Mule 63)

22

Chromosome number of:
a) Parascaris equorum
b) Oryza sativa
c) Homo sapiens
d) Pan troglodytes
e) Canis familiaris

a) 4
b) 24
c) 46
d) 48
e) 78

23

Genome size of:
a) T2 phage 170,000 bp
b) E. Coli. 4.6 million bp
c) Drosophila melanogaster 130 million bp
d) Homo Sapiens 3.2 billion bp
e) Paris Japonica 150 billion bp

a) Viruses and bacteria tend to have very small genomes
b) Prokaryotes have smaller genomes than eukaryotes
c) Sizes of plant genomes can vary dramatically

24

Chromosome number, genome size and genetic complexity

Chromosome number and genome size do not provide a valid indication of genetic complexity

25

Number of genes and biological complexity

The number of genes present in an organism will differ between species and is not a valid indicator of biological complexity