Biology Flashcards
What base goes with what base? (The pairs)
A + T
G + C
What are the four nitrogenous bases?
Thymine, guanine, cytosine, adenine.
Where is the DNA located in a cell?
In the nucleus
What type of chromosomes does a female gene have?
One pair of x’s
XX
What type of chromosomes does a male gene have?
One X and one Y
XY
What’s a gene?
A segment of DNA that is passed down from parents to children and confers a trait to the offspring
What’s DNA?
Complex giant molecule that controls all the various functions in a cell; usually organised into chromosomes and contained in the cell nucleus.
What are chromosomes?
Structure in a cell nucleus that carries the genes; each chromosomes consists of one very long strand of DNA, tightly wound
What’s Spermatozoa?
Sperm cells
What’s an ova?
A female egg
What’s Alleles?
A different form of a gene
What are autosomes?
Any chromosome that is not a sex chromosome
What are 2 differences between DNA and RNA?
RNA is a single stand and instead of having a T (thymine) base it has uracil as a nitrogenous base.
What is transcription, where does it occur?
The RNA making a copy of a section of DNA. This occurs inside the nucleus.
What’s translation? Where does it occur?
Messenger RNA (mRNA) visits Ribosomes in the cell. Here each triplet is read and coded as an amino acid. The amino acids combine to make a protein. This occurs outside the nucleus
Dominate alleles
one that is always expressed
What does DNA stand for?
Deoxyribonucleuic acid
How many autosomal chromosomes do humans have?
44
During which process is the information coded in mRNA transformed into a sequence of amino acid?
Translation
What nucleotide bonds to adenine in DNA?
Thymine
What is an example of a human cell that undergos mitosis?
Skin cell
The primary purpose of meiosis is what?
To produce gametes (sex cells)
Meiosis produces cells with the haploid or diploid number of chromosomes?
Haploid
A dominant trait is one that is expressed in a …
Heterozygous individual where they have two different alleles, but only one is expressed
If the gene that codes for normal type wings in fruit flies has the symbol N and the gene that codes for vestigial (stunted) wings has the symbol n. The genotype of heterozygous flies would be:
Nn
In a cross between a homozygous dominant individual and a homozygous recessive individual, the chance of a heterozygous child is: 25%, 50%, 75% or 100% ?
100%
The code for normal-type wings in fruit flies has the symbol N and the gene that codes for stunted wings has the symbol n. the phenotype of heterozygous flies would be?
Normal wings
The code for normal-type wings in fruit flies has the symbol N and the gene that codes for vestigial (stunted) wings has the symbol n. the genotype of stunted wing flies would be?
nn
In a cross between two homozygous dominant individuals, the chance of a heterozygous child is? 0%, 50%, 75% or 100%
0%
What do both meiosis and mitosis both involve?
The replication of DNA
A sex linked trait is one that …
Is caused by a gene carried on the X chromosome
2 heterozygous individuals are bred. The next generation is expected to be:
25% homozygous recessive, 50% heterozygous and 25% homozygous dominant
What is the sequence of the making of a DNA cell thing?
DNA Instructions ➡ transcription ➡ mRNA instructions ➡ translation ➡ amino acid sequence in protein
Transcription
The RNA making a copy of a section of DNA. This occurs inside the nucleus.
Translation
Messenger RNA (mRNA) visits Ribosomes in the cell. Here each triplet is read and coded as an amino acid. The amino acids combine to make a protein. This occurs outside the nucleus.
What are the differences between DNA and RNA?
RNA is a single stand, instead of having a T (thymine) base it has uracil as a nitrogenous base.
Who was Gregor Mendel and what did he discover?
He was a genes philosopher man. He discovered dominant and recessive genes.
What is an example of a Homozygous dominant gene? (Use letter b)
BB
What is an example of a Heterozygous gene? (Use letter b)
Bb
What is an example of a Homozygous recessive gene? (Use letter b)
bb
What is mitosis?
A type of cell division
What occurs during mitosis?
Mitosis is simply a cell dividing and becoming two cells.
Describe the process of mitosis?
The chromosomes duplicate.
They line up alone the centre of the cell and the cell membrane has disappeared.
The chromatids split at their centre and move to the opposite sides of the cell.
A cell membrane forms around each cell.
Two cells remain from one.
What is similar between the parent and daughter cell on mitosis?
They are completely identical. They have the exact same number of chromosomes and all.
What do mitosis create?
Everything except sperm and egg cells
Where does mitosis occur in the body?
All over the body in somatic (body) cells
Each time a male and a female reproduce, how many each, of their genes is passed down to the child?
One gene each, so the child gets two genes. Either XY or XX (male or female)
On what chromosome do most sex linked problems occur on? And why?
Most examples of sex-linkage that you will come across will be those of X-linkage. Because of the small size of the Y chromosomes it does not contain many genes.
Where does meiosis occur?
Reproduction organs: Gonads, (ovaries, testes) anthers.
Are the cells produced in meiosis identical to each other?
No, the cells produced are different from original cell and from each other
What is mitosis specifically used for?
It’s used for growth, development, repair and asexual reproduction
How long does mitosis take?
A couple of hours
Haploid
One copy of each specific chromosome, gametes are haploids - 23 chromosomes + gametes - meiosis
Diploid
Two copies of each specific chromosome, somatic cells are diploid - 23 pairs = 46 chromosomes altogether - mitosis
Zygote
The first initial formation of the egg and sperm
In meiosis what happens to the number of chromosomes that was in the first cell, how many are left?
The number of chromosomes in the cell is halved
Mutagens
Environmental impacts on changes to an individual
Do male or female chromosomes determine the sex of a child?
Male
What are occasional mistakes called with DNA called?
Mutations
Why do mutations occur?
Because DNA replication is a copying process involving huge numbers of base pairs
What can a tiny change in the base chain sequence do?
A tiny change in the sequence changes the amino acids being coded for which, in turn, may change the protein produced
A circle that is coloured in on a gene tree represents?
A woman affected by the gene
A plain circle on a gene tree represents?
A woman
A square on a gene tree represents?
A male
A male with a coloured in square in a gene tree represents?
A male affected by the gene
A square and a circle joined together on a gene tree represents?
No identical twins (dizygotic)
Two squares joined together represents on a gene tree?
Identical twins (monozygotic)
A diamond on a gene tree represents?
Sex unknown
A square with a line through it on a gene tree represents?
A deceased person
A circle with a spot in the centre on a gene tree represents?
A carrier of a sex linked recessive trait
What substance connects the backbone of the DNA to the nucleotides?
Sugar
What substances make up the backbone of DNA?
Phosphate and sugar
How many pairs of chromosomes do humans usually contain?
23 pairs
What is the total number of chromosomes that humans usually have? (Not in pairs)
46
Are males or females more affected by sex linked diseases? Why?
Males because females have to get two alleles to have the disease, the other X chromosome masks the disease, if they only have one then they are a carrier and do not get the disease. Males only need one allele to get the disease becuase they only have one X chromosome (the chromosome that the disease is carried on)
Are the resulting cells from meiosis haploids or diploid?
The resulting daughter cells or gametes produced by meiosis would be haploid
In meiosis, a single diploid cell ends up as?
Four haploid cells
What can a change in the base chain sequence impact?
This may then impact of the normal functioning of the organism
What’s an example of a mutation disease?
Down syndrome or Turner syndrome
In downers syndrome what is the mutation?
Extra chromosome 21
In turners syndrome what is the mutation?
Only one X chromosome (female)
DNA and genes is the mechanism by which inheritable characteristics are transmitted from …
One generation to the next
What did Crick & Watson discover in terms of DNA?
The structure
What did Franklin discover in terms of DNA?
She discovered the double helix, 3D structure
Genes determine all … features of an organism
Hereditary
Gamete
Sex cell eg sperm or egg
Homologous chromosomes
Identical pairs
Hybrid
Heterozygous alleles
Homozygous
Both alleles the same
Grigor mendals discoveries?
Basic principles of heredity
Mendel discovered that certain traits show up in offspring without any blending of parent characteristics
What are mutations?
Changes in the DNA or chromosomes
What are factors that contribute to mutations?
Radiation, chemicals/cancer causing, errors in DNA replication
Evolution
That organisms change overtime due to changing environmental conditions
What are adaptions?
Changes in an offsprings DNA because of certain factors
What are the processes involved in natural selection
Variation - isolation - mutation (genes/environment changes) - animal changes for environment - adapted offspring - genes/DNA - new species!
Variation
Favourable phenotype - contribution to gene pool
Selection
Ecosystem factors eg temperature
Competition
Individuals compete for resources, the organism that survives, breeds
Gradually a species will be well suited to its …
Environment
The … individuals survive, reproduce and pass on their genes.
best adapted
Biodiversity
The variety of plant and animal life in the world or in a particular habitat
Biodiversities importance in evolution
Without it, no trait can be advantageous over another and therefore natural selection and evolution cannot occur.
