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
interphase
chromosomes are in the process of replicating
early prophase
chromosomes are visible and appear as an X and centrioles move apart
late prophase
nuclear membrane disappear and spindle fibres form
metaphase
chromosomes line up at middle of cell and attached to spindle fibre via the centromere q
anaphase
spindle fibres pull the chromatids apart and centromeres divide and move to opposite ends of cells
telophase
nuclear membrane reforms around the chromosomes and cytoplasm divides
how many cells are created through mitosis
2
what is a diploid number
number of chromosomes in every cell of the body
diploid number of human
46
what organelle is responsible foe pulling the chromosomes apart during mitosis
centrioles and spindle fibers
when a chromosome copies itself we call this
chromatids
what is the term given to the process of division of the cytoplasm of the cell
cytokinesis
cytokinesis
process of division of the cytoplasm
male gametes in humans
sperm
female gametes in humans
egg or ovum
male gametes in animals
pollen
fertilisation
two gametes fuse together
zygote
cells that result from fertilization
meiosis
cell division to produce gametes
haploid number
half of a diploid number
how many chromosomes in a human gamete
23
stages of meiosis
Interphase prophase metaphase anaphase telophase prophase metaphase anaphase telophase
where does mitosis occur
every cell in the human body
where does meiosis occur
gonads
how many cells are produced in meiosis
4
genetic material in meiosis daughter cells
different material in each cell formed
what are mutations
permanent changes in the DNA sequence
three types of gene mutations
base substitutions
base deletions
base insertions
what is a neutral mutation
different coloured eyes
two beneficial mutations
immunity to HIV
digest lactose
what type of mutation cause huntingtons disease
insertion
effects of huntingtons
death, memory loss, lost coordination
base substitution example
sickle cell anaemia
mutations are more likely with exposure to
radiation (x rays and uv rays)
chemicals (cig smoke)
mutation from chemicals
lung cancer
mutation from uv radiation
melanoma
mutation may occur in …
somatic cells (only affect individual ) germ cells
how does down syndrome occur
nondisjunction of chromosome 21 during meiosis
nondisjunctions
error in meiosis where chromoasomes do not seperate normally
homologous chromosomes
pair of chromosomes that are inheritied from each parent
what are genes
info that control the features or characterisitcs that an individual displays
allele
different version of gene
dominant allele is represented by
capital letter
recessive allele is represented by a
lower case letter
homozygous
two identical allele on homologous chromosomes (pure breeding
heterozygous
two different allele in a chromosome (hybrid)
genotype and ex
allele pair for each characteristic eg) Bb
phenotype and ex
physical expression of an allele pair eg) blue eyes
punnet square how to write
F1 genotype and F1 phenotype
what to include in F1 genotype and phenotype
percentages
what are the sex chromosmes
23rd pair of chromosomes
the two x chromosomes in females are said to be
homologous
how do y chromosome differ from the x chromosome in males
the y chromosome is shorter with fewer genes
why are males more prone to being affected by faulty genes
if the gene on the x chromosome is faulty, then there is no chance of the male inheriting a normal gene which could mask the faulty gene
diseases that can be caused by faulty genes on the x chromosome
color blind
albinisim
which organism had its DNA sequenced first
virus
what was the human genome project
project designed to sequence DNA
name a genetic disorder that can be detected by newborn screening
cystic fibrosis
cystic fibrosis symptoms and test
heel prick
problems digesting food
type of inheritance cystic fibrosis
autosomal recessive
Bonds that bond at and gc
Hydrogen bonds
