inheritance + protein synth Flashcards
what is inheritance
Inheritance is the transmission of genetic information from generation to generation
where are chromosomes located
Chromosomes are located in the nucleus of cells
what are chromosomes
thread-like structures of DNA, carrying genetic information in the form of genes
what is a gene
A gene is a short length of DNA found on a chromosome that codes for a specific protein
what is an allele
Alleles are different versions of a particular gene
what is a haploid nucleus
a nucleus containing a single set of unpaired chromosomes (e.g. sperm and egg) hence 23 chromosomes
what is a diploid nucleus
a nucleus containing two sets of chromosomes (e.g. in body cells) hence 46 chromosomes
what are female gametes
can only carry “X” chromosomes. Hence XX pair gives female
what are male gametes
can carry “X” and “Y” chromosomes. Hence XY pair gives male
which parent is responsible for the gender of the child
only a father can pass on a Y chromosome, he is responsible for determining the sex of the child
how many sperm cells are released during ejaculation
250 million
what are the two stages of protein synthesis
transcription
translation
what occurs in transcription
rewriting the base code of DNA into bases of RNA
what occurs in translation
using RNA base sequence to build amino acids into sequence in a protein
what are some examples of proteins a gene could code for
enzymes
antibodies
receptors
Neurotransmitter
what are the four main bases
adenine
thymine
cytosine
guanine
what holds the four main bases together
phosphate backbone
which bases bond together
adenine-thymine
cytosine-guanine
how is adenine bonded with thymine
adenine forms a double hydrogen bond with thymine
how is cytosine bonded with guanine
cytosine forms a triple hydrogen bond with guanine
in a cell what are proteins made by
proteins are made by ribosomes
where are chromosomes located
inside the nucleus
what are chromatids
two lengths of a chromosome
where do chromatids join
at the centromere
how many chromosomes are there in a normal human body
23
definition of mitosis
nuclear division giving rise to genetically identical cells
first step of mitosis
Just before mitosis, each chromosome in the nucleus copies itself exactly
second step of mitosis
copy remains attached to the original, so each chromosome has 2 identical threads (known as chromatids)
third step of mitosis
the chromatids are pulled apart by cell fibres
3 functions of mitosis
Growth: mitosis produces new cells
Repair: to replace damaged or dead cells
Asexual reproduction: mitosis produces offspring that are genetically identical to the parent
what are stem cells
unspecialised cells
stem cells function
stems cell’s function is to divide via mitosis and produce new daughter cells that can become specialised in the body
main example of stem cells
zygote
how does a zygote display characteristics of a stem cell
A zygote divides several times by mitosis to become a ball of unspecialised cells (around 200-300 cells)
These are embryonic stem cells
These cells are all the same and start differentiating as the fetus develops with recognisable features
definition of meiosis and what is it used for
Meiosis is a type of nuclear division that gives rise to cells that are genetically different
It is used to produce the gametes (sex cells)
where is does meiosis take place
in the gonads of animals (testes, ovaries)
are gametes haploid or diploid
gametes are haploid as they have half the number of normal chromosomes (23)
step 1 of meiosis
Each chromosome makes identical copies of itself (forming X-shaped chromosomes)
step 2 of meiosis
First division: chromosomes pair up along the centre of the cell, recombination occurs and then cell fibres will pull the pairs apart, each new cell will have one of each recombinant chromosome pair
step 3 of meiosis
Second division: chromosomes will line up along the centre of the cell, cell fibres will pull them apart (as with mitosis)
last step of meiosis
A total of four haploid daughter cells will be produced
what is the importance of meiosis
used in the production of gametes
increases genetic variation in the offspring
how does meiosis produce variation in the offspring
Meiosis produces variation by forming new combinations of maternal and paternal chromosomes every time a gamete is made,
differences between meiosis and mitosis
meiosis:
4 cells produced (known as daughter cells)
daughter cells are haploid
daughter cells are genetically different from each other and the parent cell
two cell divisions occur
mitosis:
2 cells produced (known as daughter cells)
daughter cells are diploid
daughter cells are genetically identical to each other and the parent cell
one cell division occurs
define inheritance
Inheritance is the transmission of genetic information from one generation to the next generation
how many alleles do we have for each gene
2, as we have two copies of each chromosome and we have two copies of each gene
eg of an allele
an individual has two copies of the gene for eye colour, but one allele could code for brown eyes and one allele could code for blue eyes
what is a phenotype
The observable characteristics of an organism
what is a genotype
The combination of alleles that control each characteristic
two forms of alleles
dominant and/or recessive
how are dominant alleles inherited from parents to show up in a phenotype
only needs to be inherited from one parent
how are recessive alleles inherited from parents to show up in a phenotype
needs to be inherited from both parents
If the two alleles of a gene are the same, what is this known as
homozygous
what does it mean to be homozygous dominant
having two dominant alleles
what does it mean to be homozygous recessive
having two recessive alleles
what does it mean to be heterozygous
if the two alleles of the gene are different
in diagrams what letter is the dominant allele and what letter is the recessive allele
dominant = capital
recessive = lowercase
2 examples of stem cells
basal cells of the skin
cells in the bone marrow
when does meiosis occur
in the final stages of cell division leading to production of gametes
what is a somatic cell
cells in the body other than sperm and egg cells
how many pairs of chromosomes are there in a regular human
23 pairs
46 individual
mitosis is used for what
growth and repair
meiosis is used for what
reproduction
where is mitosis ALSO used
asexual reproduction
fourth step of mitosis
The cell divides into two; each new cell has a copy of each of the chromosomes
during protein synthesis where is the gene coding for the protein located
the gene coding for the protein remains in
the nucleus
what is a messenger RNA (mRNA)
messenger RNA (mRNA) is a molecule that carries a copy of the information in DNA to a ribosome, to be used to synthesise a protein
where are mRNA molecules made
mRNA molecules are made in the nucleus
and move to the cytoplasm
ribosomes function in protein synthesis
the ribosome assembles amino acids into
protein molecules
what is the specific sequence of amino acids in DNA determined by
the sequence of bases in the mRNA
mitosis definition
nuclear division giving rise to
genetically identical cells
definition of meiosis
reduction division in which
the chromosome number is halved from diploid
to haploid resulting in genetically different cells
what is a dominant allele
an allele that is expressed if it is present in the genotype
what is a recessive allele
an allele that is only
expressed when there is no dominant allele of
the gene present in the genotype
codominance meaning
both alleles in heterozygous organisms
contribute to the phenotype
how many chromosomes in a sperm cell
23
how many chromosomes in an egg cell
23
how many pairs of alleles in gametes
1
monohybrid cross meaning
a cross where we consider the inheritance of only one gene
where does protein synthesis occur
on the ribosomes in the cytoplasm
what does expressed mean
a gene is expressed when the protein that it codes for is synthesised in a cell
how does dna control cell functions
by controlling the production of proteins, including
enzymes, membrane carriers and receptors for
neurotransmitters
how are protiens made
the gene coding for the protein remains in
the nucleus
* messenger RNA (mRNA) is a copy of a gene
* mRNA molecules are made in the nucleus
and move to the cytoplasm
* the mRNA passes through ribosomes
* the ribosome assembles amino acids into
protein molecules
* the specific sequence of amino acids is
determined by the sequence of bases in the
mRNA
what is gene mutation
gene mutation is a change in base sequence of DNA
what is a gene mutation
a change in base sequence of DNA
what are sex-linked genes
genes that are found on a part of one of the sex chromosomes, and not on the other sex chromosome; therefore they produce characteristics that are more common in one sex than in the other
example of sex-linked genes
red-green colour blindness
what is the benefit of being heterozygous of sickle cell anaemia
more resistant to malaria
