Biology 1 Flashcards by Rina Hiraiwa

what is DNA

deoxyribonucleic acid

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what is a chromosome

a very long DNA molecule that is tightly wounded and packaged

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How many chromosomes do humans have

2 sets of 23 chromosomes (so 46 )

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where are chromosomes

in each cell in the nucleus

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why are there 2 sets of 23 chromosomes

each 23 inherited from each parent

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what is the sugar in DNA

deoxyribose

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what are the four types of nitrogen bases

adenine thymine guanine and cytosine

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what nitrogen bases bond with what?

adenine with thymine and guanine with cytosine

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what is the base pair rule?

adenine will only bond with thymine and guanine will only bond with cytosine

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what makes up a nucleotide

base, deoxyribose sugar and a phosphate

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what is DNA made up of

repeating nucleotides

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the sides of the DNA ladder are made up of alternating…

deoxyribose sugar and phosphate

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when a DNA twists it forms a

double helix

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paired bases held together by weak bonds are called

hydrogen bonds

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what is a karyotype

the number of chromosomes and their structure

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what are autosomes

22 pairs of chromosomes that carry the genes for most characteristics

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sex chromosomes

last pair of chromosomes

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what do sex chromosomes do?

carry genes for mainly gender specific characteristics

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how to know if someone had down syndrome

extra chromosome in number 21

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what chromosome is a male

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what chromosome is a female

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how many chromosomes are present in a normal human cell

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how could a karyotype be used in medicine

to diagnose particular conditions

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what is a gene

regions on the chromosome which code for a particular characteristic

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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

what is a diploid number

number of chromosomes in every cell of the body

diploid number of human

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

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

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

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