Unit 1; DNA and cell division Flashcards
griffiths experiment
injected some mice with harmless bacteria and some with disease causing bacteria the ones that were injected with this died. he thought that the disease causing bacteria made some kind of poison. he heated the disease causing bacteria up and killed them then injected them in mice; they lived. not poison? he then mixed live harmless bacteria with dead disease causing bacteria and injected that into mice and they died these dead mice were filled with the disease causing bacteria. he called this transformation.
Hershey- Chase experiment
They used radio active markers in bacteriaohage (virus made of protein and DNA that effects bacteria by attaching to the cell and inserting their genetic material)to tell whether or not the genetic information is contained within protein or DNA. They put phosphorus-32 in the DNA and sulphur-35 in the protein. the result was that the bacteria contained the phosphorus-32 therefore the genetic material came from dna
who determined the structure of DNA
james watson and francis chris
what is DNA made from
deoxyribose; a five carbon sugar, phosphate group, and a nitrogenous base; adenine, thymine, cytosine, and guanine.
purines
they have two rings; adenine and gaunine
pyrimidines
one ring; thymine and cytosine
pairing of bases
a with t and they have two hydrogen bonds. g with c and they have three hydrogen bonds.
How is DNA arranged in the cell?
DNA is coiled around protein called histones which makes a bead like structure called nucleosome which forms coils which forms super coils and eventually when cell division occurs(mitosis) they make chromosomes
differences of mRNA
ribose sugar instead of deoxyribose (which has more sugar) it is single stranded. and it contains uracil replacing thymine
genes
coded in DNA instructions that control the productions of proteins in the cell, copies part of the nucleotides from DNA into RNA
transcription
the making of RNA
transcriptase
enzyme that adds the complimentary mRNA nucleotides to DNA
types of RNA
main one you look at mRNA which is messenger RNA and it is a set of instructions for assembling amino acids into proteins. rRNA ribosomal proteins assembled on ribosomes
tRNA transfer during construction of protein tRNA transfers each amino acid to ribosome as it is specified by coded messages in mRNA.
transcription
RNA molecules are produced by copying part of the nucleotide sequence of DNA into complementary sequence. this is a process.
RNA polymerase
an enzyme that is similar to DNA polymerase. during transcription RNA polymerase binds DNA and separates DNA strands then uses the strands as template to make ran. the polymerase binds to promoters which are like signals where it should be bonded to.
Introns
part of RNA that are not involved in coding for proteins. they are cut out from mRNA because they are not needed.
Exon
DNA sequences that are used in RNA to code for proteins.
genetic code
proteins are made by joining amino acids into long chains. the chains are called polypeptides. the order of the amino acids determines the properties of the proteins.
codon
consists of three consecutive nucleotides that specify a single amino acid that is added to a polypeptide.
chargaffs rule
states that DNA from any cell of all organisms should have a 1:1 ratio (base Pair Rule) of pyrimidine and purine bases and, more specifically, that the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine.
MY THOUGHT- number of one complementary base pair is equal to the other-duh
who are crick and watson
they won the nobel prize for DNA structure
DNA polymerase
it is an enzyme that adds new complementary nucleotides to each side of the spilt DNA. IT ALSO PROOF READS IT
helicase
enzyme that splits DNA MOLECULE
ribose vs deoxyribose
ribose has more oxygen while deoxyribose has one less
nulceotide
phosphoric acid, 5 carbon sugar and a base
transcriptase
also known as RNA polymerase is an enzyme that adds complementary mRNA
how does transcription work
helicase separates the DNA molecule the enzyme transcriptase adds complementary base pairs to a strand of DNA to copy a gene to make mRNA
gene
section of DNA that performs a certain job
chromosomes
each human has 46 chromosomes- 23 homologous pairs . separated in the centre by centromeres and after the DNA is replicated there are two identical chromatids in each chromosome so like 46 pairs.
homologous pairs
same type of gene, but the gene could be be different- eye colour gene blue or brown. they are almost identical in appearance and they have the same sequence of genes along its length.
haploid
single copy of chromosome is present in the cell ( only one set of the homologous chromosome so only 23 not in pairs) sperm and egg cells - gametes.
Diploid
have homologous chromosomes- a PAIR. two copies of similar chromosomes ( one from mom and one from dad)
somatic cells
body cells that are diploid cells. the first somatic cells are called zygotes
Mitosis
process of the nucleus dividing into two nuclei
interphase
cell carries out usual cell functions necessary for life. and it prepares for cell division by doubling the amount of organelles and DNA replication occurs
prophase
chromatin condenses into chromosomes and centrioles separate. spindle forms and nuclear envelope begins to break down
metaphase
chromosomes line up across the centre of the cell and spindle fibre connects at the centromere
anaphase
sister chromatids separate into individual chromosomes and are separated
telophase
chromosomes gather at opposite ends of the cell and nuclear envelope forms,
cytokinesis
not a part of mitosis. its what occurs when the cytoplasm pinches together to make two new cells (in animal cells) and in plant cells a cell plate forms to separate the two new cells.
two reason why cells can’t get continue to grow
there is not enough DNA since there would be a higher demand on the DNA
the cell would have trouble moving nutrients into the cell and waste out of the cell. because when the surface area increases so does the volume.
process of mitosis
there are two pairs of homologous chromosomes that go through DNA replication to form two copied pairs of homologous chromosomes. those are lined up at the centre and then pulled apart to form two cells identical to parent cell.
process of meiosis
the process is the same through DNA replication. however the homologous chromosomes are separated into two different cells and then the identical chromosomes are then split. the result is 4 cells that have one of each homologous chromosome. it is like half the parent cell these are called gametes.
law of segregation
two homologous chromosomes must separate and end up in different sex cells.
law of independent assortment
homologous pairs of chromosomes are segregated independently of the other homologous chromosomes contained in the cell. basically saying it is random which creates variety.
differences between mitosis and meiosis
mitosis is short with one cell division while meiosis is a longer process with 2 cell divisions.
mitosis is asexual and meiosis is sexual.
mitosis occurs in all body cells except nerve cells and meiosis only occurs in sex organs.
mitosis makes two identical cells that are diploid cells while meiosis makes 4 genetically different haploid cells.
translation
the cell uses information from the messenger ran to produce proteins. it is done in a ribosome.
