Area of study 1

Question 1

What are the steps for translation?

Answer 1

TRNA binds to a MRNA strand matching specific amino acids, (codon to anticodon) to code for a protein. Subscripts are broken off by a ribosome and the complete polypeptide chain is released once a stop codon is reached.

Question 2

What are the steps for transcription

Answer 2

Enzyme helicase unzips double helix. RNA polymerase binds to promotor region reading the template strand from 5-3 and creating a complementary pre-MRNA strand (replacing thymine for uracil). Strands are cut into introns (cut out) exons, that are sliced and put together to make the final strand. Pre-MRNA leaves the nucleus.

Question 3

What is a gene

Answer 3

A length of DNA that contains the coded instructions for building a gene product

Question 4

What is DNA?

Answer 4

A nucleic acid composed of nucleotide monomers

Question 5

What is a genome?

Answer 5

All of the genetic material in one haploid set of chromosomes

Question 6

what causes an allele?

Answer 6

An allele is a different version of a gene, that is caused when their is a shift in DNA sequence, altering the sequence on amino acids and changing the shape of the protein, so that it changes its function.

Question 7

How is an allele inherited?

Answer 7

passed on from mother and father, however the version may differ from person to person.

Question 8

What is a chromosome?

Answer 8

a molecule of DNA coiled around histones

Question 9

What is a karyotype, and what can it determine?

Answer 9

a photograph of a persons chromosomes, can determine the individuals
- species
- sex
- some genetic abnormalities

Question 10

Autosomes are….?

Answer 10

all chromosomes except X and Y (non sex) chromosomes, do not differ between males and females

Question 11

How many autosomes do humans have?

Answer 11

22

Question 12

A mega chromosome is …?

Answer 12

A chromosome with more than 40 megabits

Question 13

A micro chromosome is ..?

Answer 13

A chromosome less than 20 megabits in length

Question 14

What do a pair of homologues chromosomes share?

Answer 14

same gene loci, size, position of centromere, banding pattern

Question 15

Phenotype

Answer 15

Physical characteristics

Question 16

Genotype

Answer 16

Genetic information

Question 17

DNA nucleotide is composed of?

Answer 17

phosphate, sugar, base

Question 18

DNA bases are held together by?

Answer 18

weak hydrogen bonds

Question 19

what is the shape of a prokaryotes chromosome/plasmid?

Answer 19

circular

Question 20

what does ploidity refer to?

Answer 20

number of chromosomes a cell has

Question 21

how many chromosomes do gametes have?

Answer 21

haploid number of chromosomes

Question 22

germ cells

Answer 22

specialized cells that give rise to gametes

Question 23

what does homogametic sex refer too?

Answer 23

individuals with two of the same sex chromosomes, (XX) female

Question 24

heterogametic sex refers to?

Answer 24

individuals with two different sex chromosomes (XY) males

Question 25

what is genetic diversity?

Answer 25

children who are not identical to their mother and father (variation in alleles)

Question 26

what are the advantages of sexual reproduction?

Answer 26

• variability in offspring (increasing chance in the most favorable traits in order to reproduce)
  -new variations have to adapt to new environments

Question 27

how many chromosomes do somatic cells have?

Answer 27

diploid 2n

Question 28

what chromosomes does a human karyotype have?

Answer 28

44 autosomes, 2 sex chromosomes

Question 29

aneuploidy refers to?

Answer 29

a genetic disorder in which one posses an abnormal number of chromosomes in somatic cells as a result of non disjunction.

Question 30

Non - disjunction in sex chromosomes

Answer 30

failure of X chromosomes to separate during meiosis

Question 31

nullisomy

Answer 31

0 homology

Question 32

monosomy

Answer 32

1 homologue

Question 33

trisomy

Answer 33

3 homolgues

Question 34

tetrasomy

Answer 34

4 homolgues

Question 35

cell division

Answer 35

a process where a parent cell divides into two daughter cells.

Question 36

crossing over

Answer 36

non-sister chromatids (bivalents) become entangled to exchange segments. Increases the genetic diversity

Question 37

Independent assortment

Answer 37

Homologous chromosomes assemble randomly along the equator to increase variation and genetic diversity in the offspring

Question 38

Steps of meiosis

Answer 38

Prophase 1: Homologues chromosomes cross over and exchange maternal and paternal parts, forming bivalents.

Metaphase 1: bivalents assemble randomly along the equator “independent assortment.”

Anaphase 1: spindle fibers shorten, and bivalents more to opposite poles.

Telophase: Cleavage furrow forms

Cytokinesis: cleavage furrow pinches off forming 2 haploid cells

Meiosis 2 - mitosis but haploid cells

Question 39

Complete dominance

Answer 39

One trait is dominant an the other is recessive, dominant being expressed in the phenotype as a heterozygous genotype

Question 40

Codominance

Answer 40

Two alleles available for a given gene locus, both being expressed in the phenotype.
red hair + white hair = red + white hair

Question 41

In-complete dominance

Answer 41

two alleles available for a given gene, neither being dominant or recessive, creating an intermediate phenotype
red + white = pink

Question 42

Hemizygous

Answer 42

Males only have one copy of X chromosome “hemi=half”

Question 43

Epigenetics

Answer 43

Heritable phenotype changes that do not involve altering the DNA sequence.

Question 44

Multiple alleles

Answer 44

A single gene has more than two alleles “blood type has A, AB, B AND O

Question 45

Epigenetic tag’s

Answer 45

can be added to histones to increase or decrease the rate at which DNA is read/transcribed.
- Methylation “decreases the rate DNA is read.” - turns off genes

-Acetylation “Increases the rate DNA is read.”
- turns on genes

Question 46

Gregor Mendel’s Laws

Answer 46

Law of segregation - alleles are separated when gametes form, each gamete carrying one allele from the gene

Law of independent assortment -the segregation of alleles for one gene is independent of the segregation of alleles for any other gene.

Law of dominance - alleles that are recessive are masked by dominant alleles

Question 47

genetic cross

Answer 47

deliberate crossing of two organisms to determine the inheritance of particular traits

Question 48

polygenetic inheritance

Answer 48

two or more genes expressed in an individuals phenotypic character

Question 49

monohybrid cross

Answer 49

crossing a homozygous dominant and a homozygous recessive individual produce a heterozygous offspring
( RR - rr)

Question 50

Autosomal monohybrid

Answer 50

two heterozygous individuals have offspring (both males and females equally affected)
(Ww - Ww)

Question 51

X-linked monohybrid

Answer 51

Females can be carriers (Xh XH - XH Y)

Question 52

Autosomal recessive

Answer 52

Both males and females affected

if one or more offspring have a different phenotype to parents

Question 53

Autosomal dominant

Answer 53

both males and females affected

most generations/all are affected

affected individuals have at least one affected parent

Question 54

X - linked recessive

Answer 54

affects more males than females
all daughters of affected males will be carriers

Question 55

X - linked dominant

Answer 55

never passed from father to son
affected females produce 1:1 affected to not affected children

Question 56

Y - linked

Answer 56

only males affected
observed in every generation males are born in

Question 57

dihybrid cross

Answer 57

inheritance patterns across two genes, that are on separate chromosomes
“FOIL” first, inside, outside, last

Question 58

Dihybrid test cross

Answer 58

A heterozygote is crossed with a homozygous individual
(Bb/Ll) - bb/ll or bl

Question 59

Figuring out pedigrees quickly

Answer 59

IF an individual has different phenotype to both parents, the trait is recessive

If there’s at least one father or son different to female ITS autosomal