Genes and Proteins

Question 1

Where are chromosomes present?

Answer 1

In every cell of the human body - every living organism has a unique genetic make up

Question 2

What cells don’t have 2 copies of every chromosome?

Answer 2

Gonads

Question 3

Where is the information carried?

Answer 3

In our DNA

Question 4

What is DNA?

Answer 4

Long-strands of ladder like structure
Double helix structure made from 2 chains
Discovered in 1050’s

Question 5

What is the DNA wrapped around?

Answer 5

Proteins, which is condensed into chromosomes in the nucleus of the cell

Question 6

What are the 2 chains of DNA made from?

Answer 6

Phosphate and deoxyribose (type of sugar)

Question 7

What does DNA consist of?

Answer 7

4 nucleotide bases
adenine
thymine
cytosine
guanine

go in pairs: a&t and c&g
ladder formed of compliments of these

Question 8

What does the genetic code consist of?

Answer 8

Chain of letters of all the nucleotide pairs together - it is that code which you unravel, and can read proteins from it - make cells determine what they will look like

Question 9

What is the purpose of DNA?

Answer 9

To make the organism individual

some is coding but some is regulatory

Question 10

How many genes are on human chromosomes?

Answer 10

Approx 23,000 genes

Question 11

What are genes?

Answer 11

Long sequences of base pairs in the DNA which encode proteins

Question 12

How are genes turned on?

Answer 12

Transcription factors

Question 13

What are transcription factors?

Answer 13

Proteins which convert DNA to RNA - in the nucleus, the genes DNA is copied into messenger RNA

transcription factor turns on a gene, making a protein

Question 14

When are transcription factors activated?

Answer 14

During development or by intracellular signalling cascades from other parts of the cell

different cells have characteristics expressed by different transcription factors - switch on the genes which are needed

Question 15

How does the transcription factor bind to a gene? How does genes to protein happen?

Answer 15

The DNA partially unravels - transcription factor goes along and copies DNA sequence to make single stranded RNA. Makes proteins out of a chain of amino acids

Question 16

How many amino acids are there?

Answer 16

Only 20 but can make loads of proteins from the different genes

Question 17

What is translation?

Answer 17

A ribosome attaches to the mRNA and moves along the mRNA, reading each triplet codon (3 bases) and using transfer RNA’s to put together the amino acid chain to make a protein

Question 18

What is mitosis and meiosis examples of?

Answer 18

A form of cell division

Question 19

What is mitosis?

Answer 19

Somatic cells (cells in our bodies) replicate to make identical copies of the DNA. the cells divide into 2 and just keep dividing and dividing into identical copies

Question 20

What is meiosis?

Answer 20

Gametes - dividing to make the DNA content which is passed onto the next generations
when the chromosomes duplicate, the cells segregate and divide, so instead of being identical, have bits from maternal and paternal chromosomes

this is what makes you different from your mum and dad

Question 21

What are the haploids?

Answer 21

These are the gamete cells - sperm or egg

Question 22

What does crossing over mean in meiosis?

Answer 22

Homologeous recombination -nucleotide sequences are exchanged between two similar or identical molecules of DNA - allows genetic diversity, by mixing up what the chromosomes look like

Question 23

Why is homologous recombination important?

Answer 23

Allows for natural selection - need diversity, so if something happens in the environment, some people will be more favourable to it than others

Question 24

Why is our DNA different to our siblings?

Answer 24

We share 50% of parents genes but a different 50% - due to meiosis

Question 25

What is mendel’s law?

Answer 25

States that during the formation of reproductive cells (gametes), pairs of hereditary factors (genes) for a specific trait separate so that offspring receive one factor from each parent

Question 26

What are the two forms of genes?

Answer 26

Dominant and recessive

Question 27

What did mendel discover?

Answer 27

Inherited properties in pea plants - tall vs dwarf. there is a trait that is controlled by a single gene

Question 28

What is it called when genes are identical?

Answer 28

Homozygous - TT or dd

Question 29

What is called when genes aren’t identical?

Answer 29

Heterozygous - Td

Question 30

What are dominant vs recessive genes?

Answer 30

dominant allele - produces a dominant phenotype in individuals who have one copy of the allele, which can come from just one parent.

recessive allele to produce a recessive phenotype, the individual must have two copies, one from each parent.

an individual with one dominant and one recessive allele for a gene will have the dominant phenotype. They are generally considered “carriers” of the recessive allele: the recessive allele is there, but the recessive phenotype is not

Question 31

What is an allele?

Answer 31

Different forms of the same gene

specifies what form the gene takes

Question 32

How many alleles do each individual have?

Answer 32

2 for each trait

Question 33

What is a genotype?

Answer 33

The possible pairings of the alleles
so either: 
BB
bb
Bb
only concerned with the pairings

Question 34

What is phenotype?

Answer 34

The expression of the trait

e.g. blue eyes

Question 35

What is a gene?

Answer 35

Specifies for the trait

Sections of DNA

Question 36

How are the 2 strands of DNA helix held together?

Answer 36

By the nucleotide base pairs

Question 37

Where are chromosomes held?

Answer 37

In the nucleus of each cell