inheritance (topic 17) Flashcards

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1
Q

chromosome

A

DNA in the nucleus of a cell is coiled and packed to form a thread-like structure,
chromosomes are made of DNA,
which contains genetic information in the form
of genes

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2
Q

gene

A

a length of DNA that codes for a
protein

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3
Q

dna

A

A large molecule made from bases, and which carries genetic information in the form of genes.

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4
Q

allele

A

An alternative version of a gene. A section of DNA that codes for a particular protein

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5
Q

what is the chromosome responsible for sex

A

XY chromsomes
xx= female
xy= male

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6
Q

haploid nucleus

A

a nucleus containing a single set of unpaired chromosomes. eg. gamete= 23 chromosomes

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7
Q

diploid nucleus

A

a nucleus containing two sets of chromosomes, for example in body cells.= 46 chromosomes (23 pairs)

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8
Q

how is sex inherited

A

each person inherits one sex chromsome from father and one from mother
sperm cell is either x or y
egg is always x

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9
Q

describe dna

A

two strands that coil together to form a double helix each strands contain complementary chemical substances called bases
T-A
C-G

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10
Q

genetic code

A

The sequence (order) of bases differs from gene to gene. The sequence of bases in a gene is its genetic code: it determines the order in which amino acids are joined together to make a specific protein

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11
Q

what does the sequence of bases in a gene determine

A

the sequence of amino acids used to
make a specific protein and different sequences of amino acids result in different shaped protein molecules

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12
Q

how does dna control cell function

A

DNA controls cell function by
controlling the production of proteins, including enzymes, membrane carriers and receptors for neurotransmitters

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13
Q

describe process of making proteins (protein synthesis)

A

-protein syntehsis occurs in ribosomes found in the cytoplasm
1. dna moelcule in nucleus unzips, exposing bases in gene
2. Mrna molecule formed using exposed bases in unzipped dna strand as template, bases in mrna bind with complementary bases in dna, mrna molecule carries a copy of the gene
3. mrna molecule moves out of the nucleus into the cytoplasm
4.ribosome reads mrna codes and joins amino acids to form protein follwoing specific base sequence in the mrna

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14
Q

true or false most body cells in an organism
contain the same genes, but many genes in a particular cell are not expressed because the cell only makes the specific proteins it needs

A

true

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15
Q

mitosis

A

nuclear division giving rise to
genetically identical cells, cells produced are called daughter cells

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16
Q

fucntions of mitosis

A

cell repair/ replacement, assexual reproduction, tissue repair,

17
Q

describe path leading to mitosis

A
  1. each chromosome is replicated exactly so that there are two copies of each chromosome
  2. chromosome join together into middle of cell
  3. when nucleus divides into two, a copy of each chromosome goes into each new cell
18
Q

stem cells

A

unspecialised cells that divide by mitosis to produce daughter cells that can become specialised for specific functions

19
Q

meiosis

A

reduction division in which the chromosome number is halved from diploid involved in production of gametes

20
Q

where are male gametes and female gametes produced

A

feamle- ovaries
male- testes

21
Q

inheritance

A

the transmission of genetic information from generation to generation

22
Q

phenotype

A

observable feature of an orgnaism

23
Q

genotype

A

genetic make-up of an organism in terms of its alleles

24
Q

homozygous

A

two identical alleles

25
Q

heterozygous

A

two different alleles

26
Q

pure breeding

A

two identical homozygous individuals
that breed together will be pure-breeding all their offspring will inherit the same alleles, and show the same phenotype as their parents

27
Q

monohybrid cross

A

Breeding two individuals that differ in their alleles for a particular gene.

28
Q

dominant allele

A

always expressed if it is present (uppercase letter symbol)

29
Q

recessive allele

A

only expressed if the dominant allele is not present. (lower case letter symbol)

30
Q

pedigree diagram

A

A type of family tree that shows the inheritance of a feature.
squares= males
circles= females

31
Q

what is meant by a carrier

A

An individual who has a single copy of a recessive allele that is responsible for a genetic disorder or disease.

32
Q

test cross

A

A cross with a homozygous recessive individual, used to determine the genotype of an individual showing the dominant trait.

33
Q

codominance

A

A situation in which two different alleles for a gene influence the phenotype to the same extent, for example in human ABO blood groups.

34
Q

what are the alleles for blood

A

I^a I^b I^o

35
Q

sex linked characteristic

A

a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other eg. red green color blindness

36
Q

describe red green colour blindness

A

sex linked chcaractersitic carried in x chromsome, which is recessive, meaning feamles have a fewer chance of getting the disease, as man only need to inherit one copy of the gene to gain the disease, while feamles must carry both, if only one recessive gene present female is a carrier