Genetics

Front 1

DNA

Back 1

A molecule which contains the 'genetic code', a set of instructions on how an organism will grow and function

Front 2

Chromosome

Back 2

A tightly folded structure of DNA and protein. They usually come in pairs.

Front 3

Nucleotides

Back 3

The building blocks of DNA. They bond together to make single strands of DNA.

Front 4

What are nucleotides made up of?

Back 4

- Phosphate group

- 5-carbon sugar

- Base

Front 5

Which base does Adenine pair with?

Back 5

Thymine

Hint 5

Straight edged ones go together

Front 6

Which base does Guanine pair with?

Back 6

Cytosine

Hint 6

Curvy ones go together

Front 7

Genome

Back 7

All the genetic information contained in a somatic cell. 23 pairs of chromosomes, 46 in total.

Front 8

How many chromosomes do humans have?

Back 8

46, 23 pairs

Hint 8

How many pairs? Double it.

Front 9

Homologous Chromosomes

Back 9

A pair of chromosomes, one maternally inherited, the other paternally.

Front 10

Karyotype

Back 10

All of the chromosomes in an organism's genome arranged from largest to smallest

Front 11

Where is DNA found?

Back 11

In the nucleus

Front 12

What are the base pairs called?

Back 12

Guanine, Cytosine, Adenine, Thymine.

Front 13

Gene

Back 13

A section of DNA that codes for a protein

Front 14

What's a triplet?

Back 14

The sequence of bases are read in sets of three (called a triplet) and contain the code for the protein.

Front 15

Protein

Back 15

Molecules in our body that determine all our traits

Front 16

What are proteins made of?

Back 16

Amino acids

Front 17

Allele

Back 17

Alternate forms of a gene. Different alleles for a for a particular gene will allow a slightly different set of bases, resulting in alternate forms of the protein.

Hint 17

Blue eyes, brown eyes, green eyes.

Front 18

Somatic Cells

Back 18

Body cells - contains a complete set of DNA

Front 19

Gametic Cells

Back 19

Sex cells - contains half of the DNA

Front 20

What must happen before mitosis or meiosis can occur?

Back 20

DNA replication

Front 21

What is DNA replication called?

Back 21

Semi conservative replication because half of the DNA is the original strand and the other half is newly made

Front 22

Sister Chromatids

Back 22

Replicated homologous chromosomes before mitosis/meiosis

Front 23

Mitosis

Back 23

When body cells divide. Produces 2 identical daughter cells.

Front 24

Interphase

Back 24

Where the DNA isn't compacted into chromosomes but is loose and genes are being expressed

Front 25

First step of mitosis?

Back 25

Prophase - DNA condenses into chromosomes

Hint 25

PMAT

Front 26

Second step of mitosis?

Back 26

Metaphase - The (replicated) chromosomes line up in the middle of the cell and fibres called spindles attach to the centre

Hint 26

PMAT

Front 27

The third step of mitosis?

Back 27

Anaphase - The spindle fibres shorten, and as they do so they pull the sister chromatids apart

Hint 27

PMAT

Front 28

The fourth step of mitosis?

Back 28

Telophase - The nuclear membrane reforms around the chromosomes

Hint 28

PMAT

Front 29

Meiosis

Back 29

A type of cell division that occurs in the ovaries and testes. Produces 4 gametes (or sex cells)

Front 30

First step of meiosis?

Back 30

Homologous chromosomes pair up

Front 31

Second step of meiosis?

Back 31

They swap sections (crossing over)

Front 32

Third step of meiosis?

Back 32

Homologous chromosomes seperate

Front 33

Benefits to sexual reproduction?

Back 33

Genetic diversity (higher chance of surviving a changing environment)

Front 34

Disadvantages of sexual reproduction?

Back 34

Takes a long time, takes a lot of energy, requires two parents

Front 35

Benefits of asexual reproduction?

Back 35

Fast, low energy cost, only requires one parent

Front 36

Disadvantages of asexual reproduction?

Back 36

No genetic diversity (if conditions become unfavourable, higher chance of the species dying out)

Front 37

What are the three ways you can have genetic variation in a population?

Back 37

Sexual reproduction, mutation and environment

Front 38

Mutation

Back 38

Changes in the base sequence of DNA resulting in different alleles

Front 39

What are mutations caused by?

Back 39

Mutagens (e.g. radiation, chemicals, viruses, x-rays, etc.)

Front 40

How can mutations be passed on to offspring?

Back 40

By being in the gametes

Front 41

N.B. about environment

Back 41

The environment doesn't affect the DNA, just whether or not you reach your genetic potential

Front 42

Genotype

Back 42

The combination of alleles for a particular trait (e.g. eye colour - BB, Bb, bb)

Front 43

Phenotype

Back 43

The physical representation of the genotype (e.g. eye colour - blue eyes or brown eyes)

Front 44

Purebreeding

Back 44

If an organism is purebred then it's homozygous for the allele that's being studied

Front 45

Test Cross

Back 45

Where you cross an individual with an unknown genotype but with a dominant phenotype) with one who is homozygous recessive. It should reveal whether the original genotype is homozygous dominant or heterozygous.

Front 46

If homozygous recessive offspring is produced during a test cross, what are the genotypes of the parents?

Back 46

Heterozygous (and homozygous recessive)

Front 47

If a women had 4 children who were all female, what is the probability that the fifth child is male?

Back 47

50%, the previous fertilisations don't influence future fertilisations. Each fertilisation is an independent event.