Biology 1 Flashcards
what is DNA
deoxyribonucleic acid
what is a chromosome
a very long DNA molecule that is tightly wounded and packaged
How many chromosomes do humans have
2 sets of 23 chromosomes (so 46 )
where are chromosomes
in each cell in the nucleus
why are there 2 sets of 23 chromosomes
each 23 inherited from each parent
what is the sugar in DNA
deoxyribose
what are the four types of nitrogen bases
adenine thymine guanine and cytosine
what nitrogen bases bond with what?
adenine with thymine and guanine with cytosine
what is the base pair rule?
adenine will only bond with thymine and guanine will only bond with cytosine
what makes up a nucleotide
base, deoxyribose sugar and a phosphate
what is DNA made up of
repeating nucleotides
the sides of the DNA ladder are made up of alternating…
deoxyribose sugar and phosphate
when a DNA twists it forms a
double helix
paired bases held together by weak bonds are called
hydrogen bonds
what is a karyotype
the number of chromosomes and their structure
what are autosomes
22 pairs of chromosomes that carry the genes for most characteristics
sex chromosomes
last pair of chromosomes
what do sex chromosomes do?
carry genes for mainly gender specific characteristics
how to know if someone had down syndrome
extra chromosome in number 21
what chromosome is a male
XY
what chromosome is a female
XX
how many chromosomes are present in a normal human cell
46
how could a karyotype be used in medicine
to diagnose particular conditions
what is a gene
regions on the chromosome which code for a particular characteristic
genome
complete genetic instructions for an organism
which cells make haemoglobin
red blood cells
what does haemoglobin do in the particular cells
carry oxygen
gene mutations for breast cancer
BRCA 1 and BRCA 2
people who helped discover DNA
Francis Crick
James Watson
Maurice Wilkins
Rosalind Franklin
what did Francis crick and James Watson do
Make models of DNA
what did rosalind franklin do
able to get two different fibers of DNA to get high resolution photos of crystallised DNA fibers
what did maurice Wilkinson do
passed on Rosalinds data to James Watson and Francis Crick
helicase
how a double helix is unwound using an enzyme
what does DNA polymerase do
Combines the thousands of nucleotides to form daughter DNA strands
which enzyme unwinds and rewinds the DNA strand
helicase
which enzyme makes the new DNA strand
DNA polymerase
chromatid
x of two replicated chromosomes
centromere
chromatid that are being held together
centriole
spindles that pull apart chromosome
mitosis stages
Interphase Prophase Metaphase Anaphase Telophase