Genetics Flashcards
What is a chromosome made out of?
Very tightly wound coils of DNA and little balls of protein
They are found in the nucleus of eukaryotic cells
What is the polymer for the monomers:
- amino acids
- sugar
- nucleotide
Polymers:
- protein
- carbohydrates
- DNA
What is DNA?
- double helix shape made of two coiled strands (deoxyribose sugar)
- sugar phosphate backbone
- 4 base pairs joined together by weak hydrogen bonds
- nucleotide monomers (phosphate=circle, sugar=pentagon, base pair =rectangle)
What is an allele?
Alleles are different forms of the same gene
What is a zygote?
Something formed when two gametes ( sex cells ) fuse
What is a phenotype?
The characteristics that we see
What is a genotype?
The allele that makes up a given feature
What does homozygous mean?
An organism that has 2 alleles that are the same for a given feature
What does heterozygous mean?
An organism that has two different alleles for a given feature
What does dominant mean?
The allele shown in an organism’s feature
What does recessive mean?
An allele that has no effect if the dominant allele is present, two of these are required to display the recessive characteristic
What is a gene?
A section of a chromosome which controls a particular feature
What sex chromosomes do males and females have?
Male = X and Y Female = X and X
Which sex cell determines the sex of the offspring?
Male
What is a punnet square used for?
They are used to work out probabilities of different phenotypes caused by alleles
Why are males more susceptible to sex linked diseases?
As the Y chromosome is significantly smaller than the X and so carries fewer genes. Therefore they often only have one allele for sex-linked genes so that characteristic is shown even if it is recessive so it is more likely to be faulty
What does the shape of a protein determine?
What is does and how it works. E.g. the shape of haemoglobin allows it to carry more oxygen as it has a larger surface area.
What would happen of the DNA was copied incorrectly?
The amino acids would be wrong, so the protein shapes would be wrong, and there would be a small effect or maybe the phenotype might even change.
What is a mutation?
A mutation is the change in the sequence of bases on the genetic code which can have neutral, negative or beneficial effects.
What does a family pedigree chart show?
The probability of genotypes and phenotypes being passes from one generation to the next from parent cells
What is the Hayflick limit?
A cell normally divides only 50 times, but when cancer comes we don’t have this counter so the cell divides uncontrollably.
What are the two types of variation?
Continuous variation can have any value between two extremes (e.g. height)
Discontinuous/discrete variation consists of specific values with nothing between (e.g. blood groups)
What are the graphs for continuous and discrete variation?
Discrete - bar graph
Continuous - line graph
Why is there variation within a species?
- There is often genetic variation within a species due to mutations (small changes in the DNA of the organism)
- sexually reproduction leading to different allele which cause different phenotypes
- environmental factors that can influence variation meaning organisms acquire characteristics
What adaptations does a polar bear have?
blubber - fat insulator
Transparent and water proof fur - as camouflage to blend into snow and catch prey
Round - smaller surface area
Black skin - to absorb and maximise heat
Big feet - large surface area so can easily walk over snow
Sharp teeth - rip open prey
Fur is thick - insulating
Claws - grip to ice
What did Mendel work with Pea plants?
- They were easy to grow
- They have many traits which helps to distinguish between them
- Their traits can be tracked from one generation to the next.
What are the 7 traits of a pea?
Flower position - top or side Stem length - tall or short seed shape - round of wrinkled Seed colour - green or yellow Seed coat colour - coloured or white Pod shape - puffed or pinched Pod colour - green or yellow
What conclusions did Mendel come to?
- characteristics in plants are determined by ‘hereditary units’
- hereditary units are passes on to offspring unchanged from both parents (one unit from each parent)
- units can be dominant or recessive, if individual has both the dominant and recessive allele, the domino characteristic will be expressed
What are the differences between DNA and RNA?
DNA
double helix
Deoxyribose sugar
ATCG
RNA
single strand
Ribose sugar
AUCG
What are the five pieces of a nucleotide?
A = adenine T = thymine C = cytosine G = guanine U = uracil
What are the stages of protein synthesis?
Transcription
Processing if the mRNA
Translation
Modification of the protein
What are the blood groups?
A, B, O, AB
Each (RBC) red blood cell has a unique and different antigen on the surface
Why must when blood is given must it be a blood type match?
Because it could clump together as the body will not recognise it, this could kill the individual
What blood types are dominant to O?
A and B
As O is a recessive blood type
O = universal donor
AB = universal receiver
How are blood types written?
I for immunoglobulin (protein in the blood) with a small letter to represent the blood group in the top right hand corner.
Hat are the genotypes for AB?
I a I b
As blood group A and B are codominant (one isn’t dominant over the other)
What are the genotypes for I (o)?
I o I o
O is recessive so to get it you must have two of the recessive alleles
Where does transcription occur?
In the nucleus of cells
What are the four bases that joint to each sugar?
A=adenine T=thymine C=cytosine G=guanine (A and T match) (C and G match)
What is the cause of a mutation?
- changes to the base sequence of DNA
- mutations that don’t have any affect are called neutral mutations
- they may affect the phenotype slightly or a big effect leading to the production of a protein so different it can no longer function
What is the human genome project?
- when thousands of global scientists collaborated in the hope to find every single human gene
- it started in 1990 and a map of around 20,500 genes was completed in 2003
- now they are researching what they all do which can be beneficial for diseases and medicine
How has the human genome project helped with the prediction and prevention of diseases?
- research may allow doctors to know what genes predisposed certain disease
- they could advice tailored lifestyles to reduce risk and check us regularly to ensure necessary early treatment
How how the human genome project helped testing and treatment for inherited disorders?
- inherited disorders are caused by the presence of one or more faulty allele in one’s genome
- has allowed these genes to be identified quicker so people can be tested for it - so better treatments or cure be developed
How had the human genome project helped to develop new and better medicines?
- scientists can use this knowledge to design drugs tailored to particular genetic variation or determine how well a drug may work
- knowing how diseases effect us in a molecular level makes it possible to design effective treatments with fewer side effects
What are some drawbacks of the human genome project?
- increased stress as if people know they are susceptible to certain diseases
- gene-ism where people with genetic problems could feel pressure not to have children
- discrimination by employers and insurance may go up for those who have genetic likelihood of serious diseases
Learn asexual and sexual reproduction
LEARN TRANSCRIPTION AND TRANSLATION
See cells and control flash card pack and hand written set
What is a genome?
The entire DNA of an organism
What are non-coding and coding regions of DNA?
Many regions of DNA are non coding meaning they don’t code for any amino acids
-some of these regions are still involved in protein synthesis as before transcription occurs RNA polymerase binds to a reign of non-coding DNA in front of the gene
How do genetic variants in the coding DNA of a gene affect the phenotype?
- If a mutation happens in a gene it produces a genetic variant
- the genetic variety may code for a different sequence of amino acids changing the shape of the final protein and so it’s activity
- this could end up changing the characteristics (phenotype)
Why did it take a while for people to recognise mendel’s work
There was no background knowledge on genes, DNA and chromosomes
- so it wasn’t until after his death that how work become significant and properly explained
- he didn’t communicate his ideas well as he couldn’t explain the science behind how inheriting characteristics worked
How do genetic variants in non-coding regions of a gene effect the phenotype?
Before transcription can happen, RNA polymerase has to bind to a region of non-coding DNA in front of a gene
- if mutations happen it can affect the ability of this binding making it easier or harder
- how well this binds affects how much mRNA is transcribed and therefore how much protein produced impacting phenotype
What is an example of one of mendel’s experiments?
- Crossed two different pea pants (one tall and one dwarf) and observed that all the offspring produced were tall
- he then bred these together and the resulting progenies where mostly tall but the small phenotype also appeared (75%/25%)
- This showed that the unit for tall plants was dominant over that for small and that each had two hereditary units
What is monohybrid inheritance?
The I herein end of a single characteristic
-can be used to show how recessive and dominant characteristics are inherited in a punnet square
How is a characteristic sex linked and what are sex linked genetic disorders?
- sex linked if the alleles that codes for it is ground on the sex chromosome
- disorders caused by faulty alleles located on sex chromosomes are called sex linked genetic disorders
Why are their four different blood types?
As the gene for blood type has 3 different alleles of which two will form an organisms genome
What can cause a mutation?
- Insertion, deletion,substitution or inversion of base pairs
- ionising radiation and mutagenic chemicals
- by chance
- can cause cell mutations and cancer (benign is slower growing and malignant is rapid growing and harder to remove)
How can a scientist improve results in reaction time?
- Include a control to get a baseline
- use intermediate sampling
- standardise volunteers e.g, through age or gender
