Genetics Flashcards
What is a gene?
Segment of DNA that contains instruction for the production of biological molecules ( such as protein. )m
pretty much codes for a particular typeof protein
What is A T , C G
DNA is composed of four different nucleotides.
Where is our DNA stored?
Almost all of our DNA is arranged into tightly coiled structures called chromosomes.
Other than the nucleus, where is a small amount of DNA found?
mitochondria
What is the ‘genome’?
All DNA contained in one cell is called the genome.
How similar is our genome compared to other people?
It is a cell which is approx 99.8% identical to every other human.
The 0.2% variation
Nucleotides differ in their sugar component.? true or false
The sugar and the phosphate parts are the same in all four nucleotides.
When heating DNA what happens?
Each double helical DNA molecule separates ( dissociation ) to form two single chains of DNA.
After cooled down, the DNA return to a double-stranded helix form ( re association )
Why are there pairs A-T and C-G
They are complementary base pairing that occur between bases in the two chains of a DNA double helix.
What are the letters called?
bases, or nucleotides
Chromatid meaning?
key word to remember:
chromosome independent
ONE of the two halves of a replicated chromosome.
Centromere meaning?
Middle, an is essential to segregation chromosome during mitosis.
Telomere meaning?
End of the chromosome. Consisting of the same short DNA sequence repeated over and over again.
Histone meaning?
It provides structural support to a chromosome.
Histone are protein molecules.
Long DNA molecules wrap around histone proteins, giving the chromosome a more compact shape, so DNA can fit into the cell nucleus.
Variation of histone?
Some variants of histones are associated with the regulation of gene expression.
allele meaning?
An allele is ONE of a pair of genes that appear at a particular location on a particular chromosome and control the same characteristic, such as blood type or colorblindness
Autosome meaning?
any chromosome that is not a sex chromosome.
Base Pairs meaning?
a pair of complementary bases in a double-stranded nucleic acid molecule,
Cytosine always pairs with guanine, and adenine with thymine (in DNA) or uracil (in RNA).
good soup
https://quizlet.com/147075887/ch-13-genomes-genes-alleles-and-chromosomes-ccw-2021-flash-cards/
Cytosine
a nitrogenous base that pairs with guanine;
when joined with sugar or phosphate, a component of nucleotides and nucleic acids
thymine
a nitrogenous base that pairs with adenine;
when joined with sugar or phosphate, a component of nucleotides and nucleic acids
adenine
a nitrogenous base that pairs with thymine; when joined with sugar or phosphate, a component of nucleotides and nucleic acids
Base sequence
The order of nucleotide bases in a DNA molecule.
How is length of DNA usually defined?
Length is usually defined as the number of base pairs
chromosome
Tightly coiled DNA that is in the nucleus of cells
deoxyribonucleic acid
DNA
Double helix
a pair of parallel helices intertwined about a common axis, especially that in the structure of the DNA molecule.
The shape of DNA
dominant
A trait that is always expressed if an allele is inherited
what isa gene overgenelised
a unit of heredity which is transferred from a parent to offspring
held to determine some characteristic of the offspring.
genomics meaning
the branch of molecular biology concerned with the structure, function, evolution, and mapping of genomes.
homologous chromosomes
a pair of chromosomes containing a maternal and paternal chromatid joined to together at the centromere.
hydrogen bonds
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
karyotype
the number and visual appearance of the chromosomes in the cell nuclei of an organism or species.
gene locus
The specific place on a chromosome where a gene is located.
non-disjunction
The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei
nucleic acids
a complex organic substance present in living cells, especially DNA or RNA,
whose molecules consist of many nucleotides linked in a long chain.
nucleotide
a compound consisting of a sugar bonded to a phosphate group and linked to a nitrogenous base . Nucleotides form the basic structural unit of nucleic acids such as DNA.
maternal
relating to or derived from the mother
paternal
related through the father
proteomics
study of the structure and function of proteins in the human body
recessive
An allele that is masked when a dominant allele if present
Chromatin
Chromatin is a substance within a chromosome consisting of DNA and protein.
when are chromosomes usually tightly coiled
usually when a cell is reproducing but usually chromosomes exist in a loose, noodle like structure
what is a chromosome?
entire chain of DNA along with a group os stablising proteins
structure of chromosomes throughout cell cycle?
interphase: fine threads
metaphase: distinct defined chromosomes
10,000 fold difference in size between DNA helix stretched out and the size of a metaphase chromosome - How?
Proteins associated with DNA
DNA plus Histones
Chromatin
What does all somatic cels have?
23 pairs of chromosomes, or 46 chromosomes
how many chromosomes does gametes have
egg or sperm have 23 chromosomes
what are gametes number called
haploids or n
what are somatic cell number called
diploid or 2n
what is karyotype used for
detect chromosomal abnormalities in human
in karyotype how are chromosomes placed in homologous pairs
- length
- banding pattern
- centromere position
what is the 23rd pair of chromosome called
sex chromosome
in karyotype where is the largest chromosome
no 1 and smallest is at the end
in karyotype where is the largest chromosome
no 1 and smallest is at the end
What can change in number of chromosome result
NON-DISJUNCTION
What can change in number of chromosome result
NON-DISJUNCTION
what is NON-DISJUNCTION
chromosome may fail to seperate during meiosis
resulting gametes to have too few or too many chromosomes
Down syndrome
three 21st chromosome
47 chromo
turner syndrome
single x chromosome
45 chromo
klinefelter syndrome
XXY chromosomes
47 chromo
abnormality for Down syndrome
trisomy 21
abnormality for turner syndrome
monosomy X
abnormality for klinefelter syndrome
xxy
HOW does structural abnormalities happen
large section of DNA are missing or added to a chromosome
when is karyotype typically taken
right or before metaphase, has two sister chromatid from 1 of two visible in one number
what does phrase ‘type of protein refer as ‘
the protein can be arranged differently which is called allele
What is alleles also
different version of a gene
homozygous
if two alleles ( one from mum and one from dad ) are the same
heterozygous
if two alleles ( one from mum and one from dad ) are the DIFFERENT
IN HETROZYGOUS what is the characteristic of the two alleles
one allele is dominant
other is recessive
when will recessive be express
when it is homozygous recessive
genotype
collection of alleles we have
so two alleles :
eg.
BB, Bb, bb
phenotype
characteristics from genotype , so expression of trait
eg. blue eyes or green
In rabbits, white fur (W) is dominant to black (w), and long ears (E) are dominant to short ears (e).
A breeder mates two rabbits that are heterozygous (WwEe) for both traits.
What is the chance that the offspring will be black with long ears?
3/16
pedigree
analysing the inheritance patterns of a trait within a family
circle pedigree
female
square pedigree
male
coloured pedigree
phenotype observed
horizontal line
marriage line , reproduced
horizontal line down
sibling line
horizontal line on edge
marriage to sibling not incest
coloured doesnt not always mean
FF or ff , observe the patterns of family
Blood type A, geno and pheno
pheno: Type A
geno:
I^A, I^A
or
I^a, OR I
Blood type A,B geno and pheno
pheno : type A
geno I^A I^B
Type O geno
ii
dominant and recessive traits are
Medeian traits
How many phenotypes in incomplete dominance
three
what is incomplete dominance
there isnt a clear dominant allele,
if R is red
r is white
Rr is pink
what is co- dominance
mix, and speckled
BOTH ARE EXPRESSED
POLYGENTIC TRAITS
various genes to determine height, skin colour, etc
epistasis
one gene depends on another gene for it to be expressed
epigenetics;
doesnt change dna but decides whether some genes are expressed in different cells in your body
methyl group
little carbon and hydrogen compounds that give outside instructions
how does methyl group control genome
by binding to a gene and saying “no not express the gene.”
histone wrap for expression of gene
more loosely = gene express more
tightly = express less
methyl and histone function like
m: switch
h: knob
genome and epigenome
genome : does the work
epigenome: tells the genome what to do
what is epigenome
protein or dna wrapped it have small chemical tags .
the tags attach to the genome of a given cell is epigenome
Methylation
an alcohol group/molecule that attaches to DNA like a tag, and interferes with how the DNA is read/suppresses the genes from being expressed
Difference between genes and alleles
A gene is a specific section of a chromosome where the base pairs that code for the characteristic are stored whereas an allele is the actual sequence of the base pairs in the section.
DNA Structure
DNA is made of chemical building blocks called nucleotides. ACGT
Translocation Karyotypes
Translocation is a type of chromosomal abnormality in which a chromosome breaks and a portion of it reattaches to a different chromosome.
Patterns of Inheritance
Autosomal recessive
Autosomal dominance
Incomplete dominance
Codominance
Autosomal recessive
Autosomal recessive inheritance is a way a genetic trait or condition can be passed down from parent to child.
Autosomal dominance
Autosomal dominance is a pattern of inheritance characteristic of some genetic diseases.
the mutated gene is a dominant gene located on one of the nonsex chromosomes (autosomes).
Gene Expression
Histone modifications
DNA methylation
Examples; stress, diet etc.
What a normal “wild type” Drosophila looks like
-wild-type fruit flies have brick-red eyes,
-yellow-brown in color
have transverse black rings across their abdomen
and wings that extend beyond their abdomen
How to distinguish between males and females.
FEMALE: pointed end, more stripes, wing is longer, abdom is longer
MALE: less stripes, darker end, shorter wings
Why they are so commonly used for genetics research.
- similar features to human
- short life cycle
- is ethical
- low chromosome and small genome size
