FHD - genetics

containing FHD topics The human genome, DNA and inheritance, Gene Expression, Protein structure

Phosphodiester bonds occur between which carbon atoms

the 3’ and 5’ carbon atoms

which two bases have two hydrogen bonds between them

Adenine and thymine

which two bases have three hydrogen bonds between them

guanine and cytosine

which end of DNA are nucleotides added to in DNA replication 

the 3’ end 

how is the lagging strains synthesised

via discontinuous replication

What way does the leading strand run

3’ to 5’

what way does the lagging strand run 

5’ to 3’ 

What does chromatin consist of

DNA and associated proteins

which type of chromatin is more compact, heterochromatin or euchromatin

heterochromatin

what is the fundamental unit of chromatin 

the nucleosome

what is a nucleosome made up of 

8 histones wrapped its 146 base pairs of DNA 

what are the different stages of the cell cycle starting from mitosis

mitosis, cytokinesis, G1, G0, S, G2

which stages of the cell cycle does interphase consist of

G1, S , G2

what is G0

a checkpoint where dividing cells are arrested at

What are checkpoints controlled by

cyclins and protein kinases 

what does chemotherapy target

both the S and M phase

what occurs in prophase

chromosomes condense and become visible, spindle fibres develop and centrioles

where are centrioles located 

at the poles of cells 

what occurs in metaphase

chromosomes align at cell equator

what occurs are anaphase

centromere divides and spindle fibres contract, pulling sister chromatids to the opposite ends of cell

what occurs in telophase 

spindle fibres break down, nuclear envelope and nucleolus reform around it 

what occurs in cytokinesis

cytoplasm divides

what makes up chromosomes

chromatin

how many mitochondrial base pairs of DNA are there 

16.6 thousand 

how many nuclear DNA base pairs are there

3.2 billion

how often is one single nucleotide polymorphism

every 1330 base pairs

At what stage of meiosis is crossing over

prophase 1 

How is a tetrad formed 

homologous chromosomes each with a pair of sister chromates line up 

how does a chiasma form 

Via sister chromatid cohesion between the adjacent chromatids of different homologs that break and rejoin

what are the two types of non-disjunction

trisomy and monosomy

what does trisomy give rise to

an extra chromosome

what does monosomy give rise to 

one less chromosome 

on what chromosomes is non-disjunction not fatal

13, 18, 21, or the sex chromosomes

what type of non-disjunction, and of which chromosome, results in Down’s syndrome

trisomy of chromosome 21

what type of non-disjunction, and of which chromosome, results in Patau’s syndrome 

trisomy of chromosome 13

what type of non-disjunction, and of which chromosome, results in Edward’s syndrome

trisomy of chromosome 18

What is the genotype of Turner’s syndrome

XO

what gender does Turner’s syndrome affect 

females

what are the symptoms of Turner’s syndrome

reduced height, underdeveloped ovaries, neck webbing, heart and kidney defects

what is the genotype of Klinefelter syndrome

XXY

what gender does Turner’s Klinefelters syndrome affect 

male

what are the symptoms of Klinefelter syndrome 

reduced fertility, it also affects general development

non-disjunction of which genotype is often not identified based on symptoms 

XXX females and XYY males 

what type of mutations produce heritable changes

germ-line mutations

what do somatic mutations contribute to

aging and disease

what are somatic cells 

all cells except germ cells 

what three systems act throughout cell life to repair DNA damage

Base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR)

what type of disease is xeroderma pigmentosum

an autosomal inherited disease

what does xeroderma pigmentosum cause 

mutation in the components of UV repair mechanism 

what is xeroderma pigmentosum linked to

acute sun sensitivity and multiple cancers

what is the quantity of RNA expressed roughly proportional to

the amount of protein generated

What is the start codon 

AUG

what does alternative splicing generate

different protein isoforms of the same gene

Where does regulation occur in terms of transcription and translation

RNA processing, translation efficiency, post translational modifications

what is miRNA 

non-coding RNA 

what does miRNA caus

transcriptional repression by binding to and degrading mRNA targets

what can the los of miRNA lead to

cancer 

Loss of which cluster gene results in b cell chromic lymphocytic leukaemia 

miR-15a/16-1 cluster gene 

Loss of which two miRNA genes result in lung cancer

miR-143 an miR-145

Which two terminals are found on an amino acid 

the amine terminal and carboxyl terminal 

there is a double bond between which two atoms in an amino acid

carbon and oxygen

what are the five different types of R groups in an amino acid 

non-polar, polar, positively charged (basic), negatively charged (acidic), aromatic 

Which R groups are hydrophobic 

Non polar aliphatic 

which R groups are hydrophilic

polar, positively charged (basic), negatively charged (acidic)

Which charge do basic R groups have, and at what pH

Positive at pH 7

What charge do acidic R groups have, and at what pH

negative at pH7

What charge do polar R groups have

no charge

What polarity are aromatic R groups

hydrophobic, but functional groups may alter polarity 

What type of bonding are the main driving force in protein folding

hydrophobic interactions

what is the main role of hydrogen bonds in protein

for stabilisation

Why are peptide bonds in the primary protein structure known as partial double bonds

they are between the length of single and double bonds

what are the four non covalent side chain interactions

electrostatic interactions, hydrogen bonding, van der waal interactions, disulphide bonds

what are van der waal interactions

electrostatic attraction due to constantly moving electrons creating slight polar charges

what are disulphide bonds 

covalently linked bonds between cystine amino acids 

what two types of beta pleated sheets can there be

parallel, or anti parallel

how often are hydrogen bonds in an alpha helix

roughly every four residues/ amino acids

what is meant by sidedness in terms of the alpha helix

charges and polar amino acids may be one one side, with hydrophobic amino acids on the other 

What are the three secondary protein structures

a beta pleated sheet, alpha helix, beta turn 

what is a beta turn

connected polypeptide chains between secondary structures such as alpha helices and beta pleated sheets 

What 

What happens (regarding entropy) when water interacts with hydrophobic molecules in the protein

the protein folds, decreasing its entropy, and increasing the entropy of the surrounding water

what is the entropy of water usually like

low as it is relatively stable

When might ionic interactions and salt bridges be stronger

when formed within more hydrophobic interiors of a protein 

what are protein domains

strict regions proteins fold into, usually having a distinct function

what are chaperones

proteins that guide other proteins to fold by interacting with it and reducing the number of molecula

what is a unique signal sequence 

a short stretch of residues (15 amino acids long)

what do unique signal sequences do

they act as postcodes for proteins

what happens to proteins without signal sequences

they remain in the cytosol

what is 45, X an example of

monosomy

what does a chiasmata form between

non sister chromatids

which strand undergoes discontinuous replication and formation

the lagging strand

Give four points of control for gene expression in the cell

• transcription

• Translation

• RNA processing

• mRNA degradation

What are the main driving forces of protein folding 

hydrophobic interactions